Mobil 1 Delvac and G50 (with LSD option)

[newjerseydave]

OK, per many recommendations here, I was going to use the Mobil 1 Delvac gear oil for my '87 911 G50 (with LSD). Then I read the following from the LN Engineering website and am more confused than ever:

"For the ultimate in protection for your gearbox, consider Millers or Joe Gibbs, however Mobil Delvac 1 is superior to the Mobil 1 gear lubes commercially available. Mobilube SHC, also known as Mobil Delvac Synthetic Gear Oil, is the factory fill from Porsche on factory cars and is different from Mobil 1 Synthetic gear lube typically sold at local auto parts stores. We recommend this gear lubricant in G50 and later manual gearboxes (or any gearboxes calling for a GL5 lubricant) for both aircooled and watercooled Porsches without limited-slip differentials. Not a limited slip gear lubricant! Although also compatible with earlier Porsche gearboxes, Swepco 201 is a better choice for these gearboxes in our personal experience (including 901 and 915, as well as VW manual gearboxes)".

Q: should I use the Delvac for a G50 with LSD??

thanks all.

[atc_marty]

I read through all the literature on this subject before I replaced my LSD G50 fluid last month. I ended up using Castrol's 75W90 synthetic gear oil since it meets all the requirements listed in the Bentley manual. It also says on the bottle that the product is "suitable for limited-slip applications". So far, so good. I figure, as long as the spec conforms to what's in the manual you can use any good product. Time will tell I guess! I would also like to hear opinions on LSD G50s running Delvac.

[Jesse16]

I'm suspicious of micro managing gear oil formulations. I'm in the camp that a good quality oil that meets the factory specs. is unlikely to let you down and unless you're actually truly racing, you're unlikely to need or ever notice "nano" technology. All that said, I sprung a little extra to put Brad Penn gear oil in mine (clear color) when the tranny was out. Took out a red color fluid from the PO which also looked clean.
Does the manual recommend a "LSD" specific formulation for your tranny ? It seems thats the only difference I see on many bottles.

[newjerseydave]

I don't believe the Manual specifically states "LS"; however, maybe it wouldn't given that limited-slip was an option on my '87 911.

Might just go with Mobil 1 75/90 LS synthetic gear oil instead now.

Any other thoughts..................

[Bill Verburg]

Delvac works fine w/ lsd, all Cups have them and use the stuff.

If you want smooth as butter shifting when cold just go to the porsche dealer and get theirs,

Delvac is made for racing transmissions and is outstanding under sever service conditions, not so much cold

[newjerseydave]

what else besides Mobil Delvac would you use in an '87 G50 with the limited slip diff. factory option?

thanks.

[Matt Monson]

I tell my clients that as a general concept LSD additives are NVH items. They make the gear oil more slippery which quiets the often chattery clutches of many oem and even certain aftermarket Lsds. But from a performance standpoint they make the LSD bite less.

That is why many in racing use an oil like Delvac. It has great high temp protection qualities and gives the LSD the best bite possible. There is no reason to use a different gear oil in your street car unless you find it too noisy or you have an issue with cold weather balky shifting on warm up.

Both GM and Motul make little bottles of LSD additive that you can add to whatever gear oil you like. Add them 1 oz at a time and see what changes you see. A little goes a long way.

Regards,

Matt Monson
Guard Transmission llc