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

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."

JFP in PA · 10-20-2009, 06:10 AM

Unfortunately, lubricants – much like politics or religion – appear to be a difficult subject to have a dispassionate or objective conversation about………….

Adam · 10-20-2009, 07:32 AM

I replaced the gear oil at 60k miles in my Mazda with Royal Purple and I'm satisfied with the purchase. It's slighty smoother especially when cold. The shifter feels like a warm knife cutting through hot butter. I just wish the shifter in the Boxster felt half as positve, smooth and easy to shift. Since it yielded an improvement in the Mazda(even though it shifted well from the start) I might try it in the Porsche if they offer the correct weight.

Frank M · 10-20-2009, 09:54 AM

Quote:

Originally Posted by Brucelee

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

Its information found in the Porsche manual, not in Frank's manual.

Also the original post was for a vehicle used in everyday service, its not a track vehicle.
Porsche's recommendation are not for track vehicles, and neither are mine.
You are on your own with a track vehicle.

Adam · 02-10-2010, 08:09 AM

I'm checking into gear oil for the Porsche trans and I'm on Redline's site. They recommend their GL-5 75W90 oil for Porsches not the GL-4. This is contradictory to what some of you are saying. I'm confused.

Here is the link.

http://www.redlineoil.com/Products.aspx?pcid=7

JackG · 02-10-2010, 09:32 AM

Quote:

Originally Posted by Adam

I'm checking into gear oil for the Porsche trans and I'm on Redline's site. They recommend their GL-5 75W90 oil for Porsches not the GL-4. This is contradictory to what some of you are saying. I'm confused.

Here is the link.

http://www.redlineoil.com/Products.aspx?pcid=7

The problem is that you would normally use a GL4 in the transmission, because as I understand it most GL5s are corrosive to the soft metals found in there (copper, brass). However, the Boxster uses the same lube in both the tranny and the differential, and the diff has hypoid gears.

Redline specifically says that their MT-90 GL4 is *not* for use with hypoid gears. They also say that their GL5 is formulated so it is not corrosive to soft metals. That's why they recommend their 75W90 GL5 for the Boxster.

Having said that, I was told by a 'reliable source" that the MT-90 was just fine to run, and I did. My shifting smoothed out, and I never had any issue with gear noise over 20k miles of use. But if I still had the car I'd swap it over to the GL5 lube, just in case.

Adam · 02-10-2010, 09:57 AM

Quote:

Originally Posted by JackG

The problem is that you would normally use a GL4 in the transmission, because as I understand it most GL5s are corrosive to the soft metals found in there (copper, brass). However, the Boxster uses the same lube in both the tranny and the differential, and the diff has hypoid gears.

Redline specifically says that their MT-90 GL4 is *not* for use with hypoid gears. They also say that their GL5 is formulated so it is not corrosive to soft metals. That's why they recommend their 75W90 GL5 for the Boxster.

Having said that, I was told by a 'reliable source" that the MT-90 was just fine to run, and I did. My shifting smoothed out, and I never had any issue with gear noise over 20k miles of use. But if I still had the car I'd swap it over to the GL5 lube, just in case.

That's what I needed to know. Thanks for the info Jack.

Frank M · 02-10-2010, 03:42 PM

Quote:

Originally Posted by Adam

I'm checking into gear oil for the Porsche trans and I'm on Redline's site. They recommend their GL-5 75W90 oil for Porsches not the GL-4. This is contradictory to what some of you are saying. I'm confused.

Here is the link.

http://www.redlineoil.com/Products.aspx?pcid=7

I wouldn't trust it.
Suppose one of your syncros fails and you get an occasional grind.
It will cost mucho bucks to fix.
I would buy the Porsche lube to have piece of mind rather than experiment.

RandallNeighbour · 02-10-2010, 04:29 PM

My mechanic is a Porsche certified tech and put Royal Purple gear oil with the appropriate weight in my 5 speed manual tranny after I swapped it for one that had a bad 1st gear synchro.

Boy howdy, if you want to kick up a dust storm, just ask about oil or tire preferences on this or any sports car forum!

Thankfully, most all of us agree on the best fuel to put in the car...

Frank M · 02-10-2010, 04:49 PM

Quote:

Originally Posted by RandallNeighbour

My mechanic is a Porsche certified tech and put Royal Purple gear oil with the appropriate weight in my 5 speed manual tranny after I swapped it for one that had a bad 1st gear synchro.

I still stick with the engineers.

Techs have opinions and usually not accountable, engineers are accountable.

I can hear a tech saying your syncro is gone because you mashed gears.

Well the gears will mash when the syncro does not bring the new gear up to the same speed as the driver gear. This causes damage to the syncro cogs.

JackG · 02-10-2010, 07:41 PM

Quote:

Originally Posted by Frank M

I still stick with the engineers.

Techs have opinions and usually not accountable, engineers are accountable.

I understand your position, except:

RMS seal failure. IMS bearing failure. D-chunk cylinder liner failure. Premature AOS and oil filler tube failures. Rear axle bearing failure. Etc, etc,...

All Porsche engineering failures. And they have NOT been held accountable.