Originally Posted By: Mike_dup1
Here we go again with this "synthetic is too slippery" myth.
The first car I put synthetic gear lube in was a new 1977 Monte Carlo with a LSD. I ordered the car with LSD as I did with all my cars and trucks. I drove that car over 100,000 miles with just one fill of Amsoil synthetic gear lube. Btw, the Monte had a Eaton, GM's preferred supplier since the 60's. Every RWD car I have ever owned since then has has a LSD (81 Olds Cutlass, 84 Olds 88 all went over 100,000 miles on the sythetic) and every one got the Amsoil synthetic gear lube. So I am talking from years of experience. I also has it in my 2002 Trans Am Thorsen LSD.
While the guys at Eaton may say not to use it, GM has been factory filling them all since about 2000 with synthetic gear lube and requires Synthetic gear lube for warranty. My 2005 CTS has LSD, it came with synthetic and has Amsoil synthetic in it now. What do they have to say about that?? GM is their largest customer.
So, this myth that synthetic is too slippery is just that, a myth. I have been using it for 30 yrs, and not once in those 30 yrs have I had so much as a seal leak in any rear axle on my vehicles.
From my CTS owners manual
Quote:
Usage Fluid/Lubricant
Rear Axle
(Limited-Slip Differential)
SAE 75W-90 Synthetic Axle
Lubricant (GM Part No. U.S.
12378261, in Canada 10953455)
meeting GM Specification 9986115.
With a complete drain and refill add
4 ounces (118 ml) of Limited-Slip
Axle Lubricant Additive (GM Part
No. U.S. 1052358, in Canada
992694) where required.
See Rear Axle on page 5-48
Mike, I wasn't expressing that I believe it to be true, but a lot of people who've run the 8.5" 10 Bolt Eaton LSDs have experienced issues running synthetic. I'm not refering to any kind of leak, but proper clutch operation. They go back to conventional oil with the additive, and their LSD worked like it should.
BuickGN,
Auburn was the stock LSD provider for the B-cars in the 90s, 8.5 10 bolt. They were cone style clutches. I don't think anyone's had issues with the cone clutches and synthetic oil.