Transmission fluid for 986 5 speed - redline?

[casioqv]

Originally Posted by ike84

You are correct that this transmission is the 012, but if you search through the forums you will find a fair number of people who have had bad experiences with mt90.

I did search as much as I could, and most people seemed to be having no problem with it. I noticed one person complaining of 'notchy' shifting, but my shifting is extremely smooth feeling.

Indeed, the logic from the redline engineer makes sense to me. Here is the full text of what they sent:

Thank you for contacting Red Line Oil, in your Boxster transaxle the 75W90NS would be recommended as the Porsche hypoid amnual transmission fluid is called for. These transaxles don’t have a high offset hypoid gear set so don’t technically require a GL-5 gear oil but that is what they call for. The MT-90 would almost provide GL-5 protection level, would be suitable but just a little different product than called for and recommended.

[JFP in PA]

Originally Posted by casioqv

I did search as much as I could, and most people seemed to be having no problem with it. I noticed one person complaining of 'notchy' shifting, but my shifting is extremely smooth feeling.

Indeed, the logic from the redline engineer makes sense to me. Here is the full text of what they sent:

Just to put his comment in context, the fluid which is made for Porsche does not have a GL rating of any kind; a small division of Royal Dutch Shell (Burhma) makes it to Porsche specs, so it completely unique.

For years, many aftermarket gear oil companies have claimed to have substitute products, but in reality, do not. Years ago, we contacted Mobil, Castrol, and several other oil company's technical groups, and the honest ones responded that the Porsche product is a "one off", and that they had no matching products.

[bcrdukes]

I have tried the cocktail and snake oils of transmission fluid in both my 996 and 986S. All have had their quirks. Having said that, the one sold by Porsche is the one that has worked best for me and I personally swear by it. Your mileage may vary.

I have never had great experiences with Redline MT-90 in a street application. Takes it a while to heat up to really work but some folks out there worship it.

[casioqv]

Originally Posted by JFP in PA

Just to put his comment in context, the fluid which is made for Porsche does not have a GL rating of any kind; a small division of Royal Dutch Shell (Burhma) makes it to Porsche specs, so it completely unique.

Any idea why Porsche would use such a custom fluid when they're just using a VW/Audi transmission that itself has a spec (VW/Audi G 052 911) that is widely matched by a lot of products?

I'd imagine maybe they are trying to tune the 'feel' of the transmission engagement for performance driving in a way VW wouldn't care about?

Still, it makes me doubt that using a VW/Audi spec oil will cause premature transmission failure.

Honestly, I didn't know all of this when I bought the MT-90. Likely I will change back to the Porsche fluid if I change it again, but in the mean time there are much more pressing maintenance issues on this 22 year old car... and I am satisfied that the MT-90 isn't likely to cause transmission failure.

[Starter986]

Originally Posted by casioqv

Any idea why Porsche would use such a custom fluid when they're just using a VW/Audi transmission that itself has a spec (VW/Audi G 052 911) that is widely matched by a lot of products?

I'd imagine maybe they are trying to tune the 'feel' of the transmission engagement for performance driving in a way VW wouldn't care about?

Still, it makes me doubt that using a VW/Audi spec oil will cause premature transmission failure.

Honestly, I didn't know all of this when I bought the MT-90. Likely I will change back to the Porsche fluid if I change it again, but in the mean time there are much more pressing maintenance issues on this 22 year old car... and I am satisfied that the MT-90 isn't likely to cause transmission failure.

So long as your feels tell you you're satiafied, you should be good. Keep up that imagination.

Me? 99% of the time I follow the advice of JFP (and a few others who do more than read...). You blaze your own trail and keep us posted on how that works out for you.

[JFP in PA]

Originally Posted by casioqv

Any idea why Porsche would use such a custom fluid when they're just using a VW/Audi transmission that itself has a spec (VW/Audi G 052 911) that is widely matched by a lot of products?

I'd imagine maybe they are trying to tune the 'feel' of the transmission engagement for performance driving in a way VW wouldn't care about?

Still, it makes me doubt that using a VW/Audi spec oil will cause premature transmission failure.

Honestly, I didn't know all of this when I bought the MT-90. Likely I will change back to the Porsche fluid if I change it again, but in the mean time there are much more pressing maintenance issues on this 22 year old car... and I am satisfied that the MT-90 isn't likely to cause transmission failure.

A retired Porsche engineer told me it is because the transmission used in the Boxster has synchro rings made from an unusual alloy that are not used in the gear box when it is in other applications. We have seen similar unique oils used in other applications for similar reasons; the one that comes to mind is the 5-speed used in late 1990's Nissan Maximas, it required a different oil than all other Nissan applications.

[casioqv]

Originally Posted by JFP in PA

A retired Porsche engineer told me it is because the transmission used in the Boxster has synchro rings made from an unusual alloy

If true that makes a lot of sense. Damn, I guess I'm changing the fluid again after all. I will be more skeptical of what I read in 101 projects from now on...

[JFP in PA]

Originally Posted by casioqv

If true that makes a lot of sense. Damn, I guess I'm changing the fluid again after all. I will be more skeptical of what I read in 101 projects from now on...

Over the years, Wayne published several "sub optimal" ideas, such as using set screws to secure the IMS shaft while doing a retrofit; not everything was off kilter, but some were real doozies............

[DreamSign]

I just (today) went to my local Porsche dealer and bought 3 liters of the 'special' gear oil. It was $35.74 per liter

The price is so close to everything else, it seemed there was really no benefit to trying anything else.