manual gear oil suggestions? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

cnavarro · 10-18-2009, 04:21 PM

I did find that Mobil does make a Delvac 1 synthetic transmission fluid 50, which is equivalent to a 90WT, which carries a GL4 rating, which is also now available in gallon jugs. Something worth asking your Mobil rep about.

Brucelee · 10-18-2009, 06:31 PM

www.redlineoil.com

Frank M · 10-19-2009, 05:35 PM

Always use the OEM lube from Porsche.
It is formulated with all the correct additives to get maximum use of syncros.
If a lube is too slippery, as many are you will get an occasional grinding in second mostly however it can occur in other gears too.
When it grinds you are damaging the cogs on both the gear and syncro.
Eventually it will always grind and subsequently slip out under a load.

A GL4 is what to use and if you contact Mobil you will find they tell you not to use their GL5 product.

Replacing the lube under 100k is usually a waste of time and money anyway.

Brucelee · 10-19-2009, 07:23 PM

Quote:

Originally Posted by Frank M

Always use the OEM lube from Porsche.
It is formulated with all the correct additives to get maximum use of syncros.
If a lube is too slippery, as many are you will get an occasional grinding in second mostly however it can occur in other gears too.
When it grinds you are damaging the cogs on both the gear and syncro.
Eventually it will always grind and subsequently slip out under a load.

A GL4 is what to use and if you contact Mobil you will find they tell you not to use their GL5 product.

Replacing the lube under 100k is usually a waste of time and money anyway.

Based on what?

Frank M · 10-20-2009, 01:28 AM

Quote:

Originally Posted by Brucelee

Based on what?

actual experience

I have seen transmissions, both automatic and manual, limited slip differentials misdiagnosed because wrong fluids.

I realize oil and other topics are passionate subjects for some with strong preferences however take what I said as not personal preferences.

OEM transmission lube is the best all around lube for all around driving in a modern Porsche and many other brands.

cnavarro · 10-20-2009, 05:00 AM

You just have to be knowlegable about lubricant choices, that's all.

Mobil's Delvac 1 isn't formulated for limited slip differentials. And yes, they do make a GL4, but again, it's not something found at your FLAPS.

As far as drain intervals, if you ask a performance transmission builder that does Porsche gear boxes, I'm sure they'll tell you to change the gear lube more often than 100,000 mi. That's way too long. If you track the car, it should really be done at least every year. Same goes with the ATF on Tip cars if tracked.

If not tracked, I would take Porsche's recommendation and cut it in half, at the very minimum.

It's interesting to see manufacturers like Kia with their very good extended powertrain warranties and see on how short their drain intervals are.

Brucelee · 10-20-2009, 05:26 AM

"I realize oil and other topics are passionate subjects for some with strong preferences however take what I said as not personal preferences.

OEM transmission lube is the best all around lube for all around driving in a modern Porsche and many other brands."

Again, I fail to understand how the above statement can be made and not seen as "personal preference."