Phokaioglaukos

I'm breaking this off into a separate thread on the chance that it will get more attention here than it has buried in lightweight flywheel thread. Hope that does not annoy you.

JasonAndreas posted: "Mobil 1 SHC 75W-90 is the latest flavor of the month (PMNA recommended : part #999.917.062.00) but unfortunately almost nobody in North America stocks it so you have to special order it and a gallon ends up costing $50USD with shipping." In addition, mds posted: "From the 2003 911 GT3 Cup Parts Catalogue, the gearbox oil is Mobilube 1 SHC 75W-90. Motorsport part# 999.917.062.00" That caused me to poke around on the web for some more information. I rapidly learned that Mobilube SHC 75W-90 has been discontinued and replaced by Mobil Delvac Synthetic Gear Oil 75W-90. These are commercial oils that are not advertised as being good for limited slip differentials that share lubricant with the transmission. A truck guy also cautioned against their use with LSDs. You can see my post and some of the links HERE .

I then called the Mobil tech info line (800.662.4525, option 3), and the fellow there cautioned that the Delvac Synthetic Gear Oil 75W-90 did not have the additives that LSDs need to lock up correctly. That makes me wonder about what the cup cars were using. Mobil 1 Synthetic Gear Lubricant LS 75W-90, which is what Bob Brooks suggests for use with the LWF, does have those additives. The Mobil tech person also cautioned against using a GL-5 oil where a GL-4 oil is specified because the more aggressive additives in the GL-5 can attack the brass components. I see that both the Delvac Synthetic Gear Oil 75W-90 and the Mobil 1 Synthetic Gear Lubricant LS 75W-90 are GL-5.

Renntech lists Approved Manual Transmission Oils as

000 043 204 20 Mobil (Mobilube PTX) - 20 liter container
000 043 204 19 Shell (Transaxle) - 20 liter container
999 917 546 00 Shell (Transaxle) - 1 liter container

The Mobil tech fellow could only tell me that Mobilube PTX is a European product only, synthetic and rated GL-4/GL-5, but he got the rating from the web site of a UK distributor, not frm Mobil. He had NO information in his Mobil database. Clearly PTX is either a rebranded Mobil product, or a specially formulated Mobil product that is Porsche specific.

I seem also to recall Brian Copans, the cup car transmission rebuilder, recommending that I stay with the Porsche-specified gear oil, but I could be wrong about that.

So, does the cup car really use an oil that Mobil cannot recommend for the street car? Does the non-GT3 996 use a different oil than the GT3? I'm pretty confused, and plan at this point to stick with the dealer-supplied Mobilube PTX, at least until someone here educates me further!

9Eleven

This is what I was told by a pretty reputable guy who races in the Rolex series. This is what he put in my car when he changed my gear oil. "We use a mixture that we make with the redline product normally 75-90 oils have a coeffient of friction of 6% modifiers. We have found better syncro control and clutch pack control with 3% -1% but 1% is too critical and a syncro can stick so we stay at 3%."

bgiere

This is the stuff, these are the guys and gals who sell it...they are very knowledgeable and will give you specifics if you call nad talk to them.

http://www.lufteknic.com/Merchant2/m...ode=lubricants

Phokaioglaukos

Brant, that's the stuff that Mobil says has been discontinued and replaced by Delvac Synthetic Gear Oil 75W-90, which is not supposed to be good for LSDs.

bgiere

true, but Luteknic still has it available...buy a couple gallons and your good for a while...BTW, i have not had that info from Mobil...Delvac name is used to bring the product in line with the other Mobil products... I am told that is simply a rebranding of the same formulations...i will double check my sources...if you do not hear back from me assume that Delvac=SHC...if not i will post the info and find an equivalent lube.

Boulder GT3

I'm glad you posted the question. I'm on my second change and couldn't get factory fill this time. I too have had a hard time getting a steady answer due to the GL4 vs. GL5 issues with LSD and synchros.

I received input from a team that campaigns GT3 with success to use Royal Purple max gear which is GL4-Gl5 rated. I called Royal Purple and they confirmed that it will do no harm to any of the brass parts and works with the LSD. FWIW.

bgiere

here is a thread i posted on BITOG.com...let's see what they come up with. i left a message with a source...will see what they say also.

http://theoildrop.server101.com/ubb/...;f=16;t=002949

enthusiast

Phokaioglaukos;

Great thread, it just shouldn't be so hard for us to take care of our machines. So what are the US Porsche Dealerships putting in the box now? Nobody wants a warranty issue over a preventative maintenance fluid change.

Phokaioglaukos

Call me Chris, it's easier to spell!

When I had the LWF installed I asked the dealer to change the gear oil. They did, using Porsche part number 999.917.546.00 which they called ORMD-transaxle oil. This is the same part number as what Renntech lists as Shell (Transaxle) - 1 liter container oil. My thought is that if I want to be certain my warranty is good to let the dealer use what Porsche tells them to use, just like I let the dealer choose the rear main seal to use. If I want the dealer to be responsible, it has to be the dealer's work.

I also sent a message to Luteknic to see what they say. You may be able to see the response HERE.

What I'm not quite following is that Mobil does not say that Mobilube 1 SHC 75W-90/Mobil Delvac Synthetic Gear Oil 75W-90 is suitable for LSD applications (the Mobil tech told me that they are TOO slippery so the LSD would not lock up properly), yet others here have quoted Porsche as specifying this oil for the GT3 cup cars! Brian Copans did explain to me that the cup car LSD is MUCH stronger than the one on my street car, so much so that he does not recommend it for use on the street out of concern that in slippery conditions or when driven by an inexperienced driver the car will just not turn. Maybe the stronger cup car LSD does not need the LSD package in the gear oil? Maybe the LSD package is just marketing? Maybe the cup car does not use copper compounds in the LSD and synchros? Although Mobil does not say that Mobilube 1 SHC 75W-90/Mobil Delvac Synthetic Gear Oil 75W-90 is suitable for LSD applications, Mobil does say that Mobil 1 Synthetic Gear Lubricant LS 75W-90 is suitable for for LSD applications. That is the gear oil that Bob Brooks suggested that I use to quiet the clatter of the transmission that the LFW does not mask as much as the dual mass flywheel.

For the moment I have fresh dealer-installed gear oil, so the matter is not pressing yet. By next year, though, I'll have to face this question head on--more Porsche oil or something different, like Mobilube 1 SHC 75W-90/Mobil Delvac Synthetic Gear Oil 75W-90 or Mobil 1 Synthetic Gear Lubricant LS 75W-90? At least the discussion of what gear oil to use seems more reasoned here than similar discussions of what motor oil to use in my Ducati!)

Larry Herman

Thanks Chris. How long do you think that 10 gallons will last me? With this car, I was told to change my gear oil every 5 events.

Boulder GT3

Does it strike anyone else as odd that this is so difficult to sort out? I'm not whining about the price, just what to pour. I've always thought Ferrari and Lambo were pretty bad about their cross marketing with AGIP so they could sell inferior products at nosebleed prices ($25/qt). The price on this isn't bad and Mobil One seems to be good prodcut but it does seem to be about 5x more complicated than it should be.

bgiere

Delvac and SHC are equivalent. They are the correct gear lube to use and are compatible with LSD.

Phokaioglaukos

I managed to get a datasheet on the Porsche-specified gear oil. It's attached along with the datasheets for the other two Mobil oils that we have been discussing. You can look for yourself, and perhaps you will actually understand, but to my layperson's mind these are NOT the same oils. The Porsche oil has different (lower?) viscosity, a higher viscosity index and a copper corrrosion rating that is not on the other two datasheets.

I hope someone can make more of this than I can!

bgiere

The additives and chemistry may be different, but the end results will be the same. they have virtually the same specs. use it with confidence! Oils will naturally change their mix as chemistry advances and new formulations are introduced...Mobilube SHC and Delvac can be safely substituted.

mxdave74

This remains a squirrely subject. Wish there was clear direction here.
I have 4 qts of Mobil 1 75w-90 LS, recommended by viper bob, but have to wonder if I shouldn't be a bit more discerning about my girls care and feeding and just head to the dealer and see what they can sell me. The mystery continues...

Dave