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Notchy shifting AFTER going to Redline fluid?


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Hi guys,

I just changed my trans fluid to Redline MT-90 and it has suddenly become more notchy. The shift itself doesn't feel bad, but the engagement between gears seems really notchy. Almost as if the synchros are having issue. Once I get past the initial effort, the shift feels great. Anyone have this happen immediately after changing their trans fluid? Only thing I can think of is that the redline is too slippery for the synchros to properly engage, although I've never had this problem in any other car (nor have I heard this as being an issue in the 986S box). BTW, this was several hundred miles ago on a 986S 6-speed box. Thanks guys.

-Tom

'01 986S

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Hi guys,

I just changed my trans fluid to Redline MT-90 and it has suddenly become more notchy. The shift itself doesn't feel bad, but the engagement between gears seems really notchy. Almost as if the synchros are having issue. Once I get past the initial effort, the shift feels great. Anyone have this happen immediately after changing their trans fluid? Only thing I can think of is that the redline is too slippery for the synchros to properly engage, although I've never had this problem in any other car (nor have I heard this as being an issue in the 986S box). BTW, this was several hundred miles ago on a 986S 6-speed box. Thanks guys.

-Tom

'01 986S

The general consensus is to use a cocktail of 2 Redline fluids:

2 parts 75W/90 NS

1 part Lightweight Gear Oil

I use this in my B&M short shifter equipped "S" and it improved the shift quality considerably. It's still a little notchy when it's cold, but way better than with the stock Porsche fluid.

redline.jpg

Good Luck,

Graeme

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Why on earth would one not use Mobil 1 Synthetic in the transmission?

Because Mobil 1 does not make a fluid with the correct GL rating to make it compatible with these transmissions...........other than that, no reason...........

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I have seen problems consistently in many cars with Redline fluid. Seems like you change it out and it causes the tranny to be notchy afterwards. I have had them even be so bad that I have saved the previous tranny fluid and put that back in the trans to fix the problem.

Light Weight Shock Proof has worked great in our race cars (nice turquoise color too lol) however I have seen it not be so happy in a few street cars as well...

The best tranny fluid for transmissions with wear problems and some grinding is actually a GM product made by Pensoil. You can buy it from any GM dealership its called GM Syncromesh. If you have a grinding or tough shifting manual tranny after about 2-3000 miles with that fluid it does a wonderful job of getting the tranny to stop grinding and causing problems. When I first heard about it I never though a GM product would be worth looking at but I kept coming at me from different sources until we tried it ourselves. I ran it in my talon for years cause they are brutal on the transmission with AWD and 400ish WHP in my personal car. Nothing but that would keep the tranny shifting smooth at 8000rpm for an entire season...

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I have seen problems consistently in many cars with Redline fluid. Seems like you change it out and it causes the tranny to be notchy afterwards. I have had them even be so bad that I have saved the previous tranny fluid and put that back in the trans to fix the problem.

Light Weight Shock Proof has worked great in our race cars (nice turquoise color too lol) however I have seen it not be so happy in a few street cars as well...

The best tranny fluid for transmissions with wear problems and some grinding is actually a GM product made by Pensoil. You can buy it from any GM dealership its called GM Syncromesh. If you have a grinding or tough shifting manual tranny after about 2-3000 miles with that fluid it does a wonderful job of getting the tranny to stop grinding and causing problems. When I first heard about it I never though a GM product would be worth looking at but I kept coming at me from different sources until we tried it ourselves. I ran it in my talon for years cause they are brutal on the transmission with AWD and 400ish WHP in my personal car. Nothing but that would keep the tranny shifting smooth at 8000rpm for an entire season...

Let's see........... We go from a gear oil with the wrong API GL rating for these gearboxes (Mobil 1), to one with no API rating at all (GM/Penzoil Syncromesh)..................yeah, that makes sense...................

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Why on earth would one not use Mobil 1 Synthetic in the transmission?

Because Mobil 1 does not make a fluid with the correct GL rating to make it compatible with these transmissions...........other than that, no reason...........

What is the correct GL rating then? Mobil 1 does make a synthetic 75W90 which is what my Bentley manual specifies. I didn't find a GL

rating in it.

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I have seen problems consistently in many cars with Redline fluid. Seems like you change it out and it causes the tranny to be notchy afterwards. I have had them even be so bad that I have saved the previous tranny fluid and put that back in the trans to fix the problem.

Light Weight Shock Proof has worked great in our race cars (nice turquoise color too lol) however I have seen it not be so happy in a few street cars as well...

The best tranny fluid for transmissions with wear problems and some grinding is actually a GM product made by Pensoil. You can buy it from any GM dealership its called GM Syncromesh. If you have a grinding or tough shifting manual tranny after about 2-3000 miles with that fluid it does a wonderful job of getting the tranny to stop grinding and causing problems. When I first heard about it I never though a GM product would be worth looking at but I kept coming at me from different sources until we tried it ourselves. I ran it in my talon for years cause they are brutal on the transmission with AWD and 400ish WHP in my personal car. Nothing but that would keep the tranny shifting smooth at 8000rpm for an entire season...

Let's see........... We go from a gear oil with the wrong API GL rating for these gearboxes (Mobil 1), to one with no API rating at all (GM/Penzoil Syncromesh)..................yeah, that makes sense...................

Wow, everybody is an expert around here. JFP do a google search on GM Syncromesh around the net. I have used it in everthing from 500hp street driven civics to RX7's with Japanese 3 Rotor right upto Supras with 800+ hp and Audi S4's with dual K04's makin around 400+whp with quattro. Guys who run major power end up with tranny issues and the GM syncromesh works wonders in all these cases. Now eventually they will need to be rebuilt however in the mean time it gave them all some extra tranny life they would have never received before. The supra especially with the Getrag tranny was grinding into 2nd pretty badly. The syncromesh all but took away 90% of the grind for another year and eventually he stripped the gear right outta the box at the drag strip, if he didn't do that who knows how much longer it would have lasted. It's a bit of an unknown trick however just because it was developed for GM doesn't mean it's bad.

I'll bet you have N rated tires on your car too eh?

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I have seen problems consistently in many cars with Redline fluid. Seems like you change it out and it causes the tranny to be notchy afterwards. I have had them even be so bad that I have saved the previous tranny fluid and put that back in the trans to fix the problem.

Light Weight Shock Proof has worked great in our race cars (nice turquoise color too lol) however I have seen it not be so happy in a few street cars as well...

The best tranny fluid for transmissions with wear problems and some grinding is actually a GM product made by Pensoil. You can buy it from any GM dealership its called GM Syncromesh. If you have a grinding or tough shifting manual tranny after about 2-3000 miles with that fluid it does a wonderful job of getting the tranny to stop grinding and causing problems. When I first heard about it I never though a GM product would be worth looking at but I kept coming at me from different sources until we tried it ourselves. I ran it in my talon for years cause they are brutal on the transmission with AWD and 400ish WHP in my personal car. Nothing but that would keep the tranny shifting smooth at 8000rpm for an entire season...

Let's see........... We go from a gear oil with the wrong API GL rating for these gearboxes (Mobil 1), to one with no API rating at all (GM/Penzoil Syncromesh)..................yeah, that makes sense...................

Wow, everybody is an expert around here. JFP do a google search on GM Syncromesh around the net. I have used it in everthing from 500hp street driven civics to RX7's with Japanese 3 Rotor right upto Supras with 800+ hp and Audi S4's with dual K04's makin around 400+whp with quattro. Guys who run major power end up with tranny issues and the GM syncromesh works wonders in all these cases. Now eventually they will need to be rebuilt however in the mean time it gave them all some extra tranny life they would have never received before. The supra especially with the Getrag tranny was grinding into 2nd pretty badly. The syncromesh all but took away 90% of the grind for another year and eventually he stripped the gear right outta the box at the drag strip, if he didn't do that who knows how much longer it would have lasted. It's a bit of an unknown trick however just because it was developed for GM doesn't mean it's bad.

I'll bet you have N rated tires on your car too eh?

Let's start with API GL ratings (you can join the API website and read all about it); the API (American Petroleum Institute) sets the testing standards for various product parameters and requirements set by the SAE (Society of Automotive Engineers, the engineers that design and test the gearbox) for use in vehicles.

Porsche (as well as many other OEM’s such as Nissan) has been using API GL-4 rated gear oils for many years. The GL-4 rating requirement stems from the use of certain alloy types in the transmission components, specifically the synchronizer and bearing assemblies. Use of a non GL-4 rated lubricant leads to premature wear or corrosion of these components, poor shifting, and potentially catastrophic component failures; which can get pretty pricey with Porsches.

Mobil 1 does not produce a GL-4 rated fluid, and in response to technical question has recommended against using their gear oils in any gearbox requiring GL-4 lubricants. GM/Pennzoil Synchromesh technical bulletins do not list any API ratings, but instead say:

“SYNCHROMESH FLUID is specifically formulated for synchromesh transmissions used by General Motors requiring General Motors Part No. 12345349 (Specification No. 9985648) Synchromesh Transmission Fluid or Chrysler transmissions requiring Part No. 4874464 (Specification MS-9224). It is also recommended for use in General Motor transmissions requiring General Motors Part No. 12345577. It is listed in the Pennzoil Lubrication Recommendation And Capacities Guide as “GLS.” PENNZOIL® SYNCHROMESH FLUID is NOT intended for all GLS applications. You must verify the manufacturer’s part number, indicated by a superscript number and found at the end of the vehicle application listing.”

Therefore, this product does not meet the API GL rating required for a Porsche. But, instead of doing individual research into what lubricants your gearbox was designed to use, please go with the "I saw it on the internet" approach, and feel free to put whatever you want into your transmission; as well, use whatever crap third world tires that floats your boat……………..

Edited by JFP in PA
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