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Slight formation of mayonnaise in oil filler cap

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Hi my wife bought last July a 2002 996 Carrera 4 with 96 000km. The full maintenance history being supplied with the (German import) car, and being a hobby mechanic, I did the maintenance incl changing spark pugs, oil (Mobil1), filters, etc... all according to the maintenace schedule provided on this site. By the way great site !

Now 7500km later, my wife tells me she got an oil level warning message. First time since 7 months I open the lid and pull out the oil dipstick. The oil level is just at the minimum mark. So I decide to top-up with some Mobil 1 and remove the oil filler cap. I was horrified to see some accumulation of crème beige thick deposit. :eek: Nothing massive, but on the inside of the cap and on the inside of the filler tube irregularly and at some places 1mm thick max. I checked again the colour of the oil with the dipstick and it is transclucent with the colour of (english beakfast )tea with no traces of intermix.

I checked the cooling water reservoir which is just above minimum level (but I do not recall at which level it stood 7 months ago) and the colour of the fluid is translucent and yellowish. No traces of mayonnaise anywhere here.

I topped up the cooling level and oil level... the engine starts well, does not smoke, runs smootly on all 6 cyl...

Could this formation of deposit in the oil filler cap be caused by the very low temperatures we experienced the last months in Belgium combined with the fact that my wife only travels 40km every day (20 in the morning and 20 in the evening) and therefore the engine nevers get hot enough to get rid of some 'natural" condensation in the crancase?? In this case this could be "normal" for a 996...

At the other hand, once the engine reaches operation temperature (which is at this season after +-10km) she got a firm foot and does not shy taking it in higher revs...

What shall I check next....coolant level and oil level (+ deposit evolution) I will certainly but shall I check the oil-cooler for faults?

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The yellowish looks stuff at the filler cap is normal for cars that are not brought to full operating temperature during drives. It is a mixture of oil and condensation from engine parts (cool -> heated).

If the oil loss was rapid then it would be wise to check for leaks as well as oil in coolant.

If both are fine then top it up (do NOT overfill) and keep an eye on it for a couple of weeks.

And to solve the yellowish stuff - get the car up to full temperature before shutting it down.

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I used to have a lot of creamy mayo looking stuff on the oil filler cap and I was told it was typical when the car is driven short distances and the engine doesn't have a chance to reach full operating temperature and have all the moisture burn off...

It freaked me out too -

But if you are driving the car to operating temperature regularly, then something else may be wrong.

BTW: oil consumption of 1quart of oil every two or three thousand miles is considered 'normal'...

Edited by roadsession
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Clean it off, take it for a good spirited drive or two or three and see if it's back.

Count me for another person that has experienced this, I used to have a 1 mile commute to work and back.

Then I stopped driving and got on the bike, no yellowish stuff forming on it.

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I'm breathing again ! :jump: I did review all the engine removal and dismantling manuals and read all te topics about "intermix" on this forum, and I was cold and warm at the same time ! Fortunately I'm missing most of the symptoms of a severe intermix problem.

Nevertheless, I will monoitor the evolution of any futher mayo in the oil filler cap and we will take in the coming weeks the car out for a couple of longer trips. Many thanks for those re-assuring words! I'm adding a picture I took when I removed the filler cap. Cleaned it up now! Rgds..

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That's a little more than what mine looked like, but not too different. It's probably not intermix, but just normal condensation. Once I cleaned it and stopped driving the car for a couple miles without ever getting to operating temp, it never came back. Now I only drive the car if I intend to warm it up to operating temp, even if it means going "the long route".

If you want to be certain it's not intermix, have a look at your coolant, what does it look like? If it looks mayonnaisey too, then there is a definately problem. With classic intermix, the oil will mix into the coolant system, but the coolant rarely mixes into the oil system.

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This is not an uncommon occurance during winter months - I'm a big believer in taking the car (any car) for a good long run (say 50 km) at highway speeds every week or so. Even revving the engine to 5-6000 rpm occasionaly during a 20km urban drive does not generate much extra heat in the system - afterall, its only for a couple of seconds, then its back to the mundane 3,000 rpm chugalong for the rest of the journey.

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  • 4 weeks later...

We drove the car longer and since then and about 1500km further down the road, there were no new signs of white/yellowish deposit anymore in the oil-filler pipe. I guess no-one needs to see a picture of that !

Many thanks to the members for their re-conforting words.

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Given Tim's travails I can understand his pessimism, but if you are not seeing contamination in the oil (on the dipstick) or in the coolant (look in the tank) I think this is just the common gunk from cold weather. Since I bought my car in 2000 I have gotten this residue in the filler neck during the winter. When I had my intermix it was way beyond what you see here. It would be worth draining the oil to take a good look at it.

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Ditto on draining the oil. That will easily tell the tale. Also had ugly stuff on dipstick. Believe me I hope its nothing. I have 996 on blocks in garage with engine out. Still not sure what to do since my cylinder heads are not recracked. Cheers!

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  • 6 months later...

You might be getting the oil to proper temp to boil out the water. Then it condenses on the long "cold" oil filler tube and mixes with the warm oil mist and "tapioca" happens. That might be part of the reason the AOS has hot water running to it.

If you ever drove a VW bug thru cold winters you would be very familiar with this stuff. Sometimes my 1965 bug would clog the first two inches of the oil filler pipe solid with this gunk. I never suspected intermix there.

Edited by fpb111
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