Mijostyn

Hi JHop,

It is not the battery or alternator. You most likely have a communications problem. Everything talks to everything through what Porsche calls a gateway module. This is done over a fiber optic bus system. When my 06 C4S went fruit loops it turned out to be a faulty PCM module. But the mechanic replaced the gateway module, the PASM computer and my instrument cluster before he finally figured it out.

If the car runs and everything works as advertised when the car is on I would just hang back, drive the car and see how things develop.

Hopefully at some point things will get bad enough that the problem will be easy to diagnose wasting less time and money. The car has default modes so it is not likely to leave you stranded although my car was stuck in track mode which made daily driving a bit rough. You will certainly need a tech with a PIWIS computer. You will be lost on your own. Just swapping parts out is a very expensive way to go with these cars.

Looks like you and I may both be right, from a Turbo press release: "To reduce drive losses and increase efficiency, an electronic on-demand oil pump is used. This means that the oil pump is operated at high power when there is high demand and at low power when there is low demand."

 

From what I can decipher from the press releases, the pump sounds mechanically driven, but with an electronic control system that can quickly vary oil pressure to engine demand.  This sounds like a bypass system which unloads the pump when the engine itself is not under load, which would also impact both HP and long term fuel consumption as well.  Apparently, Porsche has been using this concept for some time.

 Thanx JFP. It had to be something like that. The pressure jumps from 2 bar right up to 4 bar before the engine has gained 200 rpm.

The car is so complicated it is scary. I have a 7 year 100,000 mile warranty on it.

Finally did launch control last week. I did it twice and started to get sick. It pulls more Gs longer than any amusement park ride I can remember. I have no idea how that guy did it 50 times in a row.

A little light reading (from the UC Davis site) on Raoult's Law and how it applies to very dilute ideal solutions (only where the volume change upon mixing is zero, which is not the case of fuel mixing into engine oil) and in which the solute is non-volatile - for example, a solution of salt in water, which obviously does not apply to fuel, which is a volatile. Be sure to pay particular attention to the "Limitations of Raoult's law" section below:

RAOULT'S LAW AND NON-VOLATILE SOLUTES

This page deals with Raoult's Law and how it applies to solutions in which the solute is non-volatile - for example, a solution of salt in water. A non-volatile solute (the salt, for example) hasn't got any tendency to form a vapour at the temperature of the solution.

It goes on to explain how the resulting lowering of vapour pressure affects the boiling point and freezing point of the solution.

Raoult's Law

There are several ways of stating Raoult's Law, and you tend to use slightly different versions depending on the situation you are talking about. You can use the simplified definition in the box below in the case of a single volatile liquid (the solvent) and a non-volatile solute.

The vapour pressure of a solution of a non-volatile solute is equal to the vapour pressure of the pure solvent at that temperature multiplied by its mole fraction.

In equation form, this reads:

In this equation, P^o is the vapour pressure of the pure solvent at a particular temperature.

x_solv is the mole fraction of the solvent. That is exactly what it says it is - the fraction of the total number of moles present which is solvent.

You calculate this using:

Suppose you had a solution containing 10 moles of water and 0.1 moles of sugar. The total number of moles is therefore 10.1

The mole fraction of the water is:

A simple explanation of why Raoult's Law works

There are two ways of explaining why Raoult's Law works - a simple visual way, and a more sophisticated way based on entropy. Because of the level I am aiming at, I'm just going to look at the simple way.

Remember that saturated vapour pressure is what you get when a liquid is in a sealed container. An equilibrium is set up where the number of particles breaking away from the surface is exactly the same as the number sticking on to the surface again.

Now suppose you added enough solute so that the solvent molecules only occupied 50% of the surface of the solution.

A certain fraction of the solvent molecules will have enough energy to escape from the surface (say, 1 in 1000 or 1 in a million, or whatever). If you reduce the number of solvent molecules on the surface, you are going to reduce the number which can escape in any given time.

But it won't make any difference to the ability of molecules in the vapour to stick to the surface again. If a solvent molecule in the vapour hits a bit of surface occupied by the solute particles, it may well stick. There are obviously attractions between solvent and solute otherwise you wouldn't have a solution in the first place.

The net effect of this is that when equilibrium is established, there will be fewer solvent molecules in the vapour phase - it is less likely that they are going to break away, but there isn't any problem about them returning.

If there are fewer particles in the vapour at equilibrium, the saturated vapour pressure is lower.

Limitations on Raoult's Law

Raoult's Law only works for ideal solutions. An ideal solution is defined as one which obeys Raoult's Law.

Features of an ideal solution

In practice, there's no such thing! However, very dilute solutions obey Raoult's Law to a reasonable approximation. The solution in the last diagram wouldn't actually obey Raoult's Law - it is far too concentrated. I had to draw it that concentrated to make the point more clearly.

In an ideal solution, it takes exactly the same amount of energy for a solvent molecule to break away from the surface of the solution as it did in the pure solvent. The forces of attraction between solvent and solute are exactly the same as between the original solvent molecules - not a very likely event!

Suppose that in the pure solvent, 1 in 1000 molecules had enough energy to overcome the intermolecular forces and break away from the surface in any given time. In an ideal solution, that would still be exactly the same proportion.

Fewer would, of course, break away because there are now fewer solvent molecules on the surface - but of those that are on the surface, the same proportion still break away.

If there were strong solvent-solute attractions, this proportion may be reduced to 1 in 2000, or 1 in 5000 or whatever.

In any real solution of, say, a salt in water, there are strong attractions between the water molecules and the ions. That would tend to slow down the loss of water molecules from the surface. However, if the solution is sufficiently dilute, there will be good-sized regions on the surface where you still have water molecules on their own. The solution will then approach ideal behaviour.

The nature of the solute

There is another thing that you have to be careful of if you are going to do any calculations on Raoult's Law (beyond the scope of this site). You may have noticed in the little calculation about mole fraction further up the page, that I used sugar as a solute rather than salt. There was a good reason for that!

What matters isn't actually the number of moles of substance that you put into the solution, but the number of moles of particles formed. For each mole of sodium chloride dissolved, you get 1 mole of sodium ions and 1 mole of chloride ions - in other words, you get twice the number of moles of particles as of original salt.

So, if you added 0.1 moles of sodium chloride, there would actually be 0.2 moles of particles in the solution - and that's the figure you would have to use in the mole fraction calculation.

Unless you think carefully about it, Raoult's Law only works for solutes which don't change their nature when they dissolve. For example, they mustn't ionise or associate (in other words, if you put in substance A, it mustn't form A₂ in solution).

If it does either of these things, you have to treat Raoult's law with great care.

Note: This isn't a problem you are likely to have to worry about if you are a UK A level student. Just be aware that the problem exists.

Raoult's Law and melting and boiling points

The effect of Raoult's Law is that the saturated vapour pressure of a solution is going to be lower than that of the pure solvent at any particular temperature. That has important effects on the phase diagram of the solvent.

The next diagram shows the phase diagram for pure water in the region around its normal melting and boiling points. The 1 atmosphere line shows the conditions for measuring the normal melting and boiling points.

Note: In common with most phase diagrams, this is drawn highly distorted in order to show more clearly what is going on.

If you haven't already read my page about phase diagrams for pure substances, you should follow this link before you go on to make proper sense of what comes next.

Use the BACK button on your browser to return to this page when you are ready.

The line separating the liquid and vapour regions is the set of conditions where liquid and vapour are in equilibrium.

It can be thought of as the effect of pressure on the boiling point of the water, but it is also the curve showing the effect of temperature on the saturated vapour pressure of the water. These two ways of looking at the same line are discussed briefly in a note about half-way down the page about phase diagrams (follow the last link above).

If you draw the saturated vapour pressure curve for a solution of a non-volatile solute in water, it will always be lower than the curve for the pure water.

Note: The curves for the pure water and for the solution are often drawn parallel to each other. That has got to be wrong!

Suppose you have a solution where the mole fraction of the water is 0.99 and the vapour pressure of the pure water at that temperature is 100 kPa. The vapour pressure of the solution will be 99 kPa - a fall of 1 kPa. At a lower temperature, where the vapour pressure of the pure water is 10 kPa, the fall will only be 0.1 kPa. For the curves to be parallel the falls would have to be the same over the whole temperature range. They aren't!

If you look closely at the last diagram, you will see that the point at which the liquid-vapour equilibrium curve meets the solid-vapour curve has moved. That point is the triple point of the system - a unique set of temperature and pressure conditions at which it is possible to get solid, liquid and vapour all in equilibrium with each other at the same time.

Since the triple point has solid-liquid equilibrium present (amongst other equilibria), it is also a melting point of the system - although not the normal melting point because the pressure isn't 1 atmosphere.

That must mean that the phase diagram needs a new melting point line (a solid-liquid equilibrium line) passing through the new triple point. That is shown in the next diagram.

Now we are finally in a position to see what effect a non-volatile solute has on the melting and freezing points of the solution. Look at what happens when you draw in the 1 atmosphere pressure line which lets you measure the melting and boiling points. The diagram also includes the melting and boiling points of the pure water from the original phase diagram for pure water (black lines).

Because of the changes to the phase diagram, you can see that:

• the boiling point of the solvent in a solution is higher than that of the pure solvent;
• the freezing point (melting point) of the solvent in a solution is lower than that of the pure solvent.

We have looked at this with water as the solvent, but using a different solvent would make no difference to the argument or the conclusions.

The only difference is in the slope of the solid-liquid equilibrium lines. For most solvents, these slope forwards whereas the water line slopes backwards. You could prove to yourself that that doesn't affect what we have been looking at by re-drawing all these diagrams with the slope of that particular line changed.

You will find it makes no difference whatsoever.

My C4S has serially increasing fuel dilution. As time goes on more fuel is being added to the oil than boils off. (Measured by gas chromatography) so, everyone who is doing UOAs look back on your reports, plot your fuel dilution and tell us what you have. I will do the same experiment on my Turbo S. I should hit 3000 miles by the end of the Summer. (If I don't get arrested)

Oh, JFP, I noticed something interesting with the oil pressure in the Turbo. Say I'm going 75 mph in 7th gear, revs about 2000 rpm. If I step hard on the gas, boost goes up and the oil pressure shoots right up before the revs go anywhere. How does it do that?? Is the oil pump being operated by a separate electric motor?.

^Mijostyn,

^{I always enjoy reading your posts because of your analytical approach to the subject at hand. The subject of which oil brand and viscosity to use in which environment concerns me because of the risk of Intermediate shaft bearing failure and/or cylinder scoring. I can't help but think that, as you surmised, the environment has more of an impact than many of us realize. I live in Phoenix. and for a large part of the year, the oil temperature is never below 100 degrees, even when parked overnight. My 997 3.6 is as much a grocery getter as a long haul car and I put 14-16,000 miles a year on it. I am a bit paranoid about oil dilution and breakdown in the severe temperatures we see in Phoenix and use Motul Excess 5-40 with a 3,500 mile change interval. I realize that  people might think that I'm wasting oil and filters to some extent with that interval, but both are cheap compared to an engine failure. What I'm building up to here, is my concern about oil pressure in high temp environments. With oil temperature in the 225-230 degree range, my oil pressure drops to just over 1 Bar at idle while motoring about town or in heavy traffic. Once on the move, oil pressure goes up to 3 1/2-4 bar. I've considered going up a step to 10-40 or 10-50 during the summer months, but have heard that the vario-cam system is very sensitive to viscosity levels above 5-40 because of the small oil passages. You've done more research than most on the subject of which oil to use and I'd appreciate your thoughts on what direction I might go to bump up my low RPM oil pressure.}

^{Thx, Lyn.}

Hey Lyn, I almost missed your post! You live in a very warm environment. I think the Motul Excess 5W 40 you are using is perfect. Your oil pressure is absolutely fine. Just because your oil pressure looks higher with thicker oil does not mean things are squirting any better.

Your engine has oil passage ways and jets with holes of a specified diameter to work well with oils of a specific viscosity. The thicker the oil gets the harder it is to squirt which is why your pressure goes up with cold oil and oil of a higher viscosity. If the oil is too thick you may not spray stuff like your pistons as well! If you were just racing a car a 10W 50 oil would be OK as the oil temps are going to be much higher for a sustained period of time but you can't drive your car on the street like that.

You can't change your oil too early, only too late. But, I think you could easily and safely go longer than 3500 miles. Our modern synthetic oils are very tough. The limiting factor is the fuel dilution. Just do serial oil analysis on your car every 3000 miles. It only costs about $25.00. Once your oil is 2% diluted you are done. In my car that happens by 6000 miles. The oil otherwise is in great shape.

Just change your oil filter and send the oil in the filter housing to the lab, replace the filter and top your oil off, about 1/2 liter.

Well, personally I would say you have nailed it. Thank you for finding all this out. It makes sense of Porsche's comments in the manual and also my own observations. I will keep doing a long run on a regular basis to allow me to get an accurate oil reading as my usual run to and from work on a daily basis is only a 4 mile round trip. Oil changes at every 6,000 miles or less I think. No way 20,000!

Fraid not. But you are probably right jl-c. Change your oil more frequently. If you want to know how frequent do serial UOAs on your car. All of the reliable references I have found recommend to change your oil at a fuel dilution of 2%. A good article on this is at www.machinerylubrication.com/Atricles/Print/1304

OK, here is where I'm at as of this juncture:

• Everyone I have spoken to (oil company technical personnel, used oil analytical labs) has basically said the same thing: When fuel dilutes the oil, a very small (read minute) amount of the oil's ingredients may react with the fuel and form compounds that may be more difficult to separate from the oil, but even that change does not in any way impede a laboratory from separating the fuel from the oil in both a quantitative and qualitative manner. The most common technique used to determine both the quantity of fuel in the oil, and to analyze this fuel effluent to confirm that it truly is fuel, is head space gas chromatography. In this technique, the oil sample is gradually heated up to between 300 and 350F so that the instrument can determine both the temperature at which the effluent comes off, and compare the analytical data of the individual components of the effluent with stored known sample data bases to confirm that it actually is fuel. From this technique, the lab can tell you both how much came off as a percentage of the sample mass, and confirm that it is fuel and not some other diluent. Using gas chromatography, or flame ionization chromatography which is able to do the same test with even higher levels of accuracy, this analytical technique is considered to be both accurate and extremely reproducible.
• No one that I have spoken with concurs with the idea that diluent fuel mixed with common commercial synthetic engine oil will not flash off under normal engine operating conditions found in a Porsche oil sump (coolant around 200-215F, oil around 230-240F, partial vacuum of around 5 inches of water). And as these conditions are "nominal", meaning that the engine, coolant, and oil are often hotter under warmer ambient conditions, higher speed driving, or aggressive driving situations; the engine should therefore have no problem ridding itself of most, if not all, of the highly volatile components found in normal gasoline. One individual even noted that water, which boils at a much higher temperature than gasoline, will completely boil off from engine oil at a little over 200F at 5 inches of water vacuum, well within the normal operating conditions of a Porsche engine.
• Used oil analytical labs I spoke with were fairly adamant in their response to fuel dilution levels continuing to rise in sequential oil samples from the same engine. The common response was one of two possibilities: Either the engine had a worsening problem that accelerated the fuel dilution problem with time, or the analytical technique used to determine the level of dilution was flawed. While some noted that as oil aged in use, it was possible for the breakdown by products of the oil itself to flash off at lower temperatures, which could lead to some confusion over the actual amount of fuel in the oil, but noted that either gas chromatography or flame ionization should recognize and discount these by products as not part of normal gasoline, and therefore not count them as being from fuel.

So at this point, I will have to throw the topic back open for further discussion, and welcome input from anyone with other observations or data.

Hey JFP, miss me? ;-)

Polaris uses Gas Chromatography. The Flame Ionization Detector is the gizmo used in the gas chromatograph to quantify the various fractions. A little hydrogen flame ionizes the molecules increasing the current through the detector. The time and duration identify the substance. What separates the substances is not their vapor pressure but the speed at which they pass through various mediums on their way to the FID. I finally remembered the name of the guy who got me into all this trouble, Francois-Marie Raoult. Raoult's law attempts to sort of quantify the interaction between varying molecules in solution. Don't get too dizzy when you read it. I only make it through the first couple of equations. In one sense I was wrong. There is a relation to vapor pressure but the effect is that it mostly averages out. This is only in solutions of like substances. As soon as you put polar molecules in nonpolar solutions or visa versa they just repel each other. Which is why the water boils off. Good thing too as I can't stand the thought of my engine rusting! Still hate that white crud on the oil filler cap.

I looked into it, according to what I just read, Raoult’s Law applies at limiting low concentrations for non-volatile solutes. At higher concentrations or with volatile solutes, different compounds behave differently.

Are you sure that is the correct reference?

And no, I didn't miss you..................... :eek:

The total vapor pressure of a solution of non polar molecules such as fuel in oil is, P = p*A XA + p*B XB + ........

P*A is the partial pressure of molecule A and XA is the mole fraction of that substance in the solution and so forth for molecules B, C and onwards. The individual vapor pressure of a given molecule is Pi = Pi* Xi . i is for the sake of the example fuel. Pi is the vapor pressure of fuel in the mixture. Pi* is the vapor pressure of pure fuel and Xi is the mole fraction of the fuel in the mixture. For simplification let's call the mole fraction the simple percentage of fuel in the mixture fuel in oil. This is actually quite close. In our example that would be 2%. Thus Xi is 0.02 and the vapor pressure of fuel is only 2% of the vapor pressure the fuel would normally have. This means that the fuel evaporates at such a slow rate that it is essentially inconsequential and as time goes on the fuel dilution just continues to increase as fuel is being added to the mixture much faster than it can evaporate. This is exactly what the labs are telling us and what my C4S has done, they just don't know why.

The fact of the mater is that fuel does not just "flash off" regardless of temperature. That is just a myth based on a knee jerk comprehension of the problem. Unfortunately, it seems that this myth is believed by many people in important places that should know better. Then those of us that do not have the comprehensive background needed to understand this stuff are deluded into thinking that the myth is true. And away we go.

These discussions are great stuff for all of us. They force use to review and rethink our beliefs in search of the truth not one ups man ship. None of us should feel stupid in the face of these discussions as none of us can learn absolutely everything about this universe.

We all specialize in our own area of expertise.

Come on JFP. I know you miss me.

GC-FID I feel my past catching up with me... :huh:

I'm still buried in it Loren. We use all this stuff in medicine. What really is annoying is that my old brain is not near as nimble as it use to be. In my 20s I would see an equation and visualize immediately what it was telling me. Now things are not as immediate or clear. What is it that Einstein said about getting old? Something about you just get dumber?

Well, personally I would say you have nailed it. Thank you for finding all this out. It makes sense of Porsche's comments in the manual and also my own observations. I will keep doing a long run on a regular basis to allow me to get an accurate oil reading as my usual run to and from work on a daily basis is only a 4 mile round trip. Oil changes at every 6,000 miles or less I think. No way 20,000!

Fraid not. But you are probably right jl-c. Change your oil more frequently. If you want to know how frequent do serial UOAs on your car. All of the reliable references I have found recommend to change your oil at a fuel dilution of 2%. A good article on this is at www.machinerylubrication.com/Atricles/Print/1304

OK, here is where I'm at as of this juncture:

• Everyone I have spoken to (oil company technical personnel, used oil analytical labs) has basically said the same thing:  When fuel dilutes the oil, a very small (read minute) amount of the oil's ingredients may react with the fuel and form compounds that may be more difficult to separate from the oil, but even that change does not in any way impede a laboratory from separating the fuel from the oil in both a quantitative and qualitative manner.  The most common technique used to determine both the quantity of fuel in the oil, and to analyze this fuel effluent to confirm that it truly is fuel, is head space gas chromatography.  In this technique, the oil sample is gradually heated up to between 300 and 350F so that the instrument can determine both the temperature at which the effluent comes off, and compare the analytical data of the individual components of the effluent with stored known sample data bases to confirm that it actually is fuel.  From this technique, the lab can tell you both how much came off as a percentage of the sample mass, and confirm that it is fuel and not some other diluent.  Using gas chromatography, or flame ionization chromatography  which is able to do the same test with even higher levels of accuracy, this analytical technique is considered to be both accurate and extremely reproducible.
• No one that I have spoken with concurs with the idea that diluent fuel mixed with common commercial synthetic engine oil will not flash off under normal engine operating conditions found in a Porsche oil sump (coolant around 200-215F, oil around 230-240F, partial vacuum of around 5 inches of water).  And as these conditions are "nominal", meaning that the engine, coolant, and oil are often hotter under warmer ambient conditions, higher speed driving, or aggressive driving situations; the engine should therefore have no problem ridding itself of most, if not all, of the highly volatile components found in normal gasoline.  One individual even noted that water, which boils at a much higher temperature than gasoline, will completely boil off from engine oil at a little over 200F at 5 inches of water vacuum, well within the normal operating conditions of a Porsche engine.
• Used oil analytical labs I spoke with were fairly adamant in their response to fuel dilution levels continuing to rise in sequential oil samples from the same engine.  The common response was one of two possibilities: Either the engine had a worsening problem that accelerated the fuel dilution problem with time, or the analytical technique used to determine the level of dilution was flawed.  While some noted that as oil aged in use, it was possible for the breakdown by products of the oil itself to flash off at lower temperatures, which could lead to some confusion over the actual amount of fuel in the oil, but noted that either gas chromatography or flame ionization should recognize and discount these by products as not part of normal gasoline, and therefore not count them as being from fuel.

So at this point, I will have to throw the topic back open for further discussion, and welcome input from anyone with other observations or data.

Hey JFP, miss me? ;-)

Polaris uses Gas Chromatography. The Flame Ionization Detector is the gizmo used in the gas chromatograph to quantify the various fractions. A little hydrogen flame ionizes the molecules increasing the current through the detector. The time and duration identify the substance. What separates the substances is not their vapor pressure but the speed at which they pass through various mediums on their way to the FID. I finally remembered the name of the guy who got me into all this trouble, Francois-Marie Raoult. Raoult's law attempts to sort of quantify the interaction between varying molecules in solution. Don't get too dizzy when you read it. I only make it through the first couple of equations. In one sense I was wrong. There is a relation to vapor pressure but the effect is that it mostly averages out. This is only in solutions of like substances. As soon as you put polar molecules in nonpolar solutions or visa versa they just repel each other. Which is why the water boils off. Good thing too as I can't stand the thought of my engine rusting! Still hate that white crud on the oil filler cap.

sp-design you just park it in the hot sun for an hour and the film comes right off. James, yes the old 3M stuff degrades over time. The Xpel is supposed to be better but up here in the north it is going to take a lot of abuse from stones and such which is the point. Better to mess up your film than your paint. the film on my speed yellow 06 C4S is looking pretty ratty. If I do not sell it next year I will have it done in Xpel. Clean paint increases the market value of the car so you get the money back in the end.

fwiw - I bought a 2009 black 911C4S last year which had the front end covered with film (I think it was 3M) and it was quite badly dulled/yellowed after four or so years.

 

It was bad enough that I had it removed by the dealer as a condition of purchase.

the question to consider is - have you ever taken old film off of a car.   the film on my previous cayman s started to look bad, gray spots and lines.  it is a major league PITA to remove.  i found it best to start by heating it with a hair dryer, then peel one of the corner of the hood loose, then wrap it around a 3/4" wood dowel ... pull evenly and wrap it around the dowel and keep pulling.   that way its a lot easier on your hands and tends to keep it from breaking / tearing into smaller pieces.  didn't spend the money to put it on my 997 when i bought it. 

Excellent. I'll check with Polaris to see which method they are using, but no It does not contradict my theory which is really not my theory at all. I am just parroting what I learned. They are probably looking at the concentration of a specific molecule found in gas but not in oil. If you know the concentration of that molecule in both clean gas and clean oil then once you determine the concentration of that molecule in the "dirty" oil vapor you also now know what its concentration in the "dirty" oil is. They have to vaporize the mess for the test to work. I am not sure how inaccurate flash point analysis is but you are certainly not directly measuring fuel dilution. The other tests directly measure the concentration probably of specific molecules. I wonder how the various formulas the oil blenders use affect these tests as well as there may be some variation in gasoline composition. But, when I think about it all this is essentially null as I am sure Polaris used the exact same test on all my oil samples and there is an undeniable trend. The 1st sample at 1000 miles o.75 % diluted, the 2nd at 3000 miles 1.6 % diluted then at 6000 3.4% diluted. The fuel is certainly not vaporizing off faster than the oil is being diluted over a period of about 7 months!

More to the point, I've been talking to labs that do UOA work, and a couple have told me that if a lab is using flash point analysis (cheap, quick, but grossly inaccurate) to determine fuel dilution levels, that alone can generate results similar to what you saw.  From my discussion's with them, the recommended method to do fuel dilution in engine oils is by head space gas chromatography, or by flame ionization chromatography.   While they seem to feel that flame ionization is the more accurate of the two methods, both only heat the oil sample to 300F to get the fuel off for measurement in the dector.  That point alone seems to contradict your theory.

 

I'm going to keep digging on this subject.  I have inquiries into contacts I have inside the oil industry (started my career off working in the R&D group of one of the then big ones) to see if they can shed any light on the subject.

 

Stay tuned.................

Hey Offroad aehsani is right, just call Suncoast. Only a Porsche dealer can order the wheel. They are great with this stuff. But if the wheel is not cracked, just bent, it can be safely straightened. Rule of thumb is if the defect is not easy to see until you spin the wheel it can be straightened. If the defect is painfully obvious just looking at the wheel it is trashed. There is a gray zone in the middle. A crack always trashes the wheel. I feel your pain. I have black wheels on my C4S. Back then they used crappy paint on the wheels so eventually I had to have them all powder coated. One was bent a little but now you would never know. There are companies that true wheels all over the place.

Another way some people deal with this is by getting a set of less expensive, easier to replace OZ wheels and put the originals in the attic for safe keeping. You can even get center lock wheels now.

It is funny how we develop these mythologies. Humans are funny creatures. When we do not know what is going on we make stuff up! Then the made up stuff gets a life and away we go. A good example is the gluten fad. I have to deal with this stuff every day. Most of the myths have some basis in reality. All substances have a vapor pressure which varies based on the nature of the substance and temperature. The molecules in gas as a conglomerate have a higher vapor pressure than the conglomerate molecules in motor oil. But, when you put them in solution together all bets are off. Think of it this way. Is the vapor in your crank case near as explosive as the vapor in a gas can. It does not take much gas vapor to cause quite the explosion!

 

 

 

 

Luxter, reading the manual. (we all do don't we?) it appears that Porsche agree with you and what I did to boil off excess fuel/condensation from my oil, I quote:-

Engine Oil

Engine oil consumption

It is normal for your engine to consume oil.

The rate of oil consumption depends on the quality

and viscosity of oil, the speed at which the engine

is operated, the climate, road conditions as well

as the amount of dilution and oxidation of the

lubricant.

If the vehicle is used for repeated short trips, and

consumes a normal amount of oil, the engine oil

measurement may not show any drop in the oil

level at all, even after 600 miles (1,000 km) or

more. This is because the oil is gradually becoming

diluted with fuel or moisture, making it appear

that the oil level has not changed.

The diluting ingredients evaporate out when the

vehicle is driven at high speeds, as on an expressway,

making it then appear that oil is excessively

consumed after driving at high speeds.

If the conditions you drive your vehicle in are

dusty, humid, or hot, the frequency of the oil

change intervals should be greater.

 

Seek and ye shall find  :D

Oil change this weekend (6,000 m), going away from Mobil 1 and using Castrol Edge 5W 40, but have just purchased oil for the next change and gone for the Millers Oils NANODRIVE CFS 5w-40 NT as recommended on here. Time will tell which suits the best. Intend to get analysis done every 3,000 m to keep an eye on things and get a comparison between them

 

 

 

Hey jl-c, I just put Edge 5W 40 in the Turbo S. This is what Audi uses so I have a common oil with My wife's SQ5 for the time being. I plan to switch both cars to Millers after they hit 10,000 miles (broken in). That Porsche recommendation is only 1/2 right. Moisture (H2O) does indeed boil off as you heat up the oil but fuel does not. Once the oil is diluted with fuel it is permanent. If you look at the UOAs of my C4S as you get more miles the fuel dilution only increases in a linear fashion. By 6,000 miles the oil is diluted enough to lose a viscocity grade. So, I do not go longer than 6000 mile between oil changes in that car. Each car is different so, the only way to know what is going on with your car is to run serial UOAs until you have it figured out. Porsche's recommended oil change interval is more political than anything. You can go 10,000 miles but I wouldn't, at least not in my C4S.

 

Millers is the absolute best as Luke's, mine and now Dus10R's experience shows. I am absolutely sure that wear rates fall off with this oil formulation.

 

 

I'm not sure I can agree with your comments on fuel dilution.  Nearly all the components in gas have considerably higher vapor pressures than water, so if the water is boiling off, the fuel should have preceded it.  I think the issue may be how (the analytical technique) your UOA lab is measuring fuel dilution, they may be seeing accumulating fuel additive's that remain after the fuel actually flashed off, which would give the impression of increasing fuel dilution with time.

 

 

It has nothing to do with vapor pressure JFP. It has to do with solubility and the polarity of the various molecules. I discussed this before when I explained fractional distillation. This is a mistake many people make. The UOAs are quite predictible in this reguard and reasonably accurate. Fuel does not boil off once it is desolved in oil. In order to separate it you have to heat it all up to 1000 degrees and catch the molecules as they condense. This is how oil refineries work. Non polar molecules attract each other in solution but repell polar molecules such as water. This is why the water boils off.

 

 

I am going to have to look into this subject a bit deeper; I am find many references to the fuel dilution flashing off when an engine reaches both full operating temperatures, and some level of vacuum in the sump, and nothing (yet) to support your point.  We will come back to this topic.................

 

Anyway, Just call Millers oil in England. I bring up Millers because you can actually get to someone who knows what they are talking about and they can be most helpful. I doubt you will get the same treatment from Mobil or Shell.

 

 

Luxter, reading the manual. (we all do don't we?) it appears that Porsche agree with you and what I did to boil off excess fuel/condensation from my oil, I quote:-

Engine Oil

Engine oil consumption

It is normal for your engine to consume oil.

The rate of oil consumption depends on the quality

and viscosity of oil, the speed at which the engine

is operated, the climate, road conditions as well

as the amount of dilution and oxidation of the

lubricant.

If the vehicle is used for repeated short trips, and

consumes a normal amount of oil, the engine oil

measurement may not show any drop in the oil

level at all, even after 600 miles (1,000 km) or

more. This is because the oil is gradually becoming

diluted with fuel or moisture, making it appear

that the oil level has not changed.

The diluting ingredients evaporate out when the

vehicle is driven at high speeds, as on an expressway,

making it then appear that oil is excessively

consumed after driving at high speeds.

If the conditions you drive your vehicle in are

dusty, humid, or hot, the frequency of the oil

change intervals should be greater.

 

Seek and ye shall find  :D

Oil change this weekend (6,000 m), going away from Mobil 1 and using Castrol Edge 5W 40, but have just purchased oil for the next change and gone for the Millers Oils NANODRIVE CFS 5w-40 NT as recommended on here. Time will tell which suits the best. Intend to get analysis done every 3,000 m to keep an eye on things and get a comparison between them

 

 

 

Hey jl-c, I just put Edge 5W 40 in the Turbo S. This is what Audi uses so I have a common oil with My wife's SQ5 for the time being. I plan to switch both cars to Millers after they hit 10,000 miles (broken in). That Porsche recommendation is only 1/2 right. Moisture (H2O) does indeed boil off as you heat up the oil but fuel does not. Once the oil is diluted with fuel it is permanent. If you look at the UOAs of my C4S as you get more miles the fuel dilution only increases in a linear fashion. By 6,000 miles the oil is diluted enough to lose a viscocity grade. So, I do not go longer than 6000 mile between oil changes in that car. Each car is different so, the only way to know what is going on with your car is to run serial UOAs until you have it figured out. Porsche's recommended oil change interval is more political than anything. You can go 10,000 miles but I wouldn't, at least not in my C4S.

 

Millers is the absolute best as Luke's, mine and now Dus10R's experience shows. I am absolutely sure that wear rates fall off with this oil formulation.

 

 

I'm not sure I can agree with your comments on fuel dilution.  Nearly all the components in gas have considerably higher vapor pressures than water, so if the water is boiling off, the fuel should have preceded it.  I think the issue may be how (the analytical technique) your UOA lab is measuring fuel dilution, they may be seeing accumulating fuel additive's that remain after the fuel actually flashed off, which would give the impression of increasing fuel dilution with time.

 

It has nothing to do with vapor pressure JFP. It has to do with solubility and the polarity of the various molecules. I discussed this before when I explained fractional distillation. This is a mistake many people make. The UOAs are quite predictible in this reguard and reasonably accurate. Fuel does not boil off once it is desolved in oil. In order to separate it you have to heat it all up to 1000 degrees and catch the molecules as they condense. This is how oil refineries work. Non polar molecules attract each other in solution but repell polar molecules such as water. This is why the water boils off.

Luxter, reading the manual. (we all do don't we?) it appears that Porsche agree with you and what I did to boil off excess fuel/condensation from my oil, I quote:-

Engine Oil

Engine oil consumption

It is normal for your engine to consume oil.

The rate of oil consumption depends on the quality

and viscosity of oil, the speed at which the engine

is operated, the climate, road conditions as well

as the amount of dilution and oxidation of the

lubricant.

If the vehicle is used for repeated short trips, and

consumes a normal amount of oil, the engine oil

measurement may not show any drop in the oil

level at all, even after 600 miles (1,000 km) or

more. This is because the oil is gradually becoming

diluted with fuel or moisture, making it appear

that the oil level has not changed.

The diluting ingredients evaporate out when the

vehicle is driven at high speeds, as on an expressway,

making it then appear that oil is excessively

consumed after driving at high speeds.

If the conditions you drive your vehicle in are

dusty, humid, or hot, the frequency of the oil

change intervals should be greater.

 

Seek and ye shall find  :D

Oil change this weekend (6,000 m), going away from Mobil 1 and using Castrol Edge 5W 40, but have just purchased oil for the next change and gone for the Millers Oils NANODRIVE CFS 5w-40 NT as recommended on here. Time will tell which suits the best. Intend to get analysis done every 3,000 m to keep an eye on things and get a comparison between them

 

 

 

Hey jl-c, I just put Edge 5W 40 in the Turbo S. This is what Audi uses so I have a common oil with My wife's SQ5 for the time being. I plan to switch both cars to Millers after they hit 10,000 miles (broken in). That Porsche recommendation is only 1/2 right. Moisture (H2O) does indeed boil off as you heat up the oil but fuel does not. Once the oil is diluted with fuel it is permanent. If you look at the UOAs of my C4S as you get more miles the fuel dilution only increases in a linear fashion. By 6,000 miles the oil is diluted enough to lose a viscocity grade. So, I do not go longer than 6000 mile between oil changes in that car. Each car is different so, the only way to know what is going on with your car is to run serial UOAs until you have it figured out. Porsche's recommended oil change interval is more political than anything. You can go 10,000 miles but I wouldn't, at least not in my C4S.

Millers is the absolute best as Luke's, mine and now Dus10R's experience shows. I am absolutely sure that wear rates fall off with this oil formulation.

Up North I'm all for Black interiors, easy to keep new looking. Next black 911 get one with a red interior/black carpets or red and black two tone. VERY sharp!

5 seconds is the fastest I've seen. The manual will do 4.8. These times are for the S. Remember the Japs over rate their cars.

Hi Chirag,

Sure beats an SUV doesn't it? Even the Cayenne turbo S. You don't want to display a Mercedes to Porsche Guys ;-) It is a good thing it is hers or we would not let you on the site.

You like inflicting yourself with black cars. 911s are sharp in black. What's the interior?

You have to love these guys. I'll just get a copy from my mechanic the next time I see him which obviously won't be too far off. I just want to keep a copy of the bulletin with the car's service documents....for the record. This is why Porsche uses new stuff like these composite brakes on limited edition cars initially. If things screw up you limit the damage and with new technology like this, things always screw up. There have already been multiple revisions. However these brakes are worth the battle. They are better in every way except cost. They are better looking, they don't rust, they are wonderfully clean and they stop like CRAZY. It is always funny to watch a newbie drive the car. They always over cook the brakes throwing themselves against the seat belt. I never warn them :-)

Hey 63356, I just picked up a 2014 911 Turbo S and I had the whole front of the car, hood, fenders, lights and mirrors covered in Xpel.

Not one single person including my mechanic has realized it was covered until I told them. The surface quality and clarity of the film are superior to 3M products. There are two down sides. It is more expensive than 3M film because the film costs 1/2 again as much and it is harder to install. When you cut a line into regular polyurethane film you can not tear the film beyond the cut. Xpel will not stop. It will keep tearing along a line of stress like paper. It is much easier to ruin a piece of expensive film during installation thus the price is increased to cover the added cost. Even the best installer will ruin a piece on occasion.

I watched my car being done and the installer, Leonardo (no kidding) is a real artist. Autobahn obviously sends him to do the custom installs on cars like this. I do not think I could ever be as good at it. Leonardo cut everything free hand! I have never seen a steadier hand with a knife.

Anyway, Xpel is much better looking than Clear Bra (3M), You can cover whole panels thus no lines. It is just as protective which takes a lot of the stress out of driving these beautiful cars. It is worth every cent. Over the life of the car it will save me hundreds of hours of work repairing chips and the car will hold its value better. Anyone buying a new 911 or a used one in excellent condition or reprinted is nuts not to have the car covered in this stuff. This is most definitely what I call a premier product. There is none better.

Oh, and I use Rejex on the whole car Xpel included. This is the toughest most slippery, shiny, water repellent paint sealant I have ever used. It treats the Xpel just like the rest of the car. I do not see any reason why all of the paint sealant/ waxes would not work on Xpel but everyone should try Rejex. The only trick to Rejex is that once you wipe it on you do not want to let it sit more than a couple of minutes. It starts polymerizing immediately making it tough to rub out if you let it sit too long. You just do a section at a time. If you want the wax look just put the wax on over the Rejex.

Tails, do you have the Bose system?

RJN, Loren, Is it possible to display the actual document??

It's a bit hidden in PIWIS. The search engine seems poor and doesn't find stuff. I got it from drilling down -  ie set the car type as 2014 Turbo S then, Information media, SY - Symptom-based repair instructions, Transmission/suspension/brakes.

RJN have your ordered your Turbo S yet??

Thanx Loren! It is coming off tonight.

 

Loren,

 

Could you tell me how to get a hold of TSB WM465155??

 

I just did a PIWIS search and it came back "not found". So it has ether just been released or has not been released yet.

Have you asked your local dealer for a printed copy?

 

No, but I will. Did not think about it when I picked the car up. The mechanic mentioned that he "found a bulletin on it."  I have the clicking problem and Porsche is aware of it but apparently has not come up with a solution yet. They say the car is totally safe to drive. There is some tolerance issue with the spring loaded system that mounts the disc to the hub. I guess they plan to replace everyone's rotors once they figure it out. The only info I got was "the parts are not yet available" and "don't call us we'll call you."

Loren,

Could you tell me how to get a hold of TSB WM465155??

Great Ogun. If you have not plugged a tire yet try practicing on an old tire. Just bang a nail into it. The reemer takes quite a bit of force you have to twist it as you push it into the tire. You want to have the plug ready to go on the insertion tool covered in rubber cement. When you pull the insertion tool out of the tire do it in one aggressive fast tug. Cut off the excess plug. You can drive on it immediately. Also, do not do this on a flat tire. You won't be able to push the reemer in. Inflate the tire first. It will hold air long enough. Once I had a tire cut by a piece of sheet metal. It made a slice 3/4 inch long. I had to use three plugs! And, it held air just fine. The plugs and cement age in time and become hard. I change them once yearly. Oh and never plug a side wall. Side wall injuries are always fatal.

Thanx Hobbes. Unfortunately, the 991 is a little different than the 996/997 cars but I suspect the mounting system is pretty similar. You have to be careful with the new cars as the Audi influence has taken over a lot of the construction details and techniques. As an example the gas door mechanism is totally Audi. The oil filter housing design is totally Audi. This is not a bad thing at all. The new car has a jewel like quality missing from the older cars. The interior design is much more cohesive

ala Audi. But, the car goes ala PORSCHE!

Just finished talking to the guys at Sound in Motion and they told me just to slip a plactic spatula in at the top and pop it straight outwards then up out of the dash.

Will give it a try tonight.