Gear Oil

[kcirdnek]

Okay, I tried the search for my specific car for this answer but nothing came back. So, I'm just going to ask. I have a 1996 Chevrolet Impala SS with a 8.5" rear end. I am going to rebuild the rear end in the next couple of months. I am upping to 3.73 gears with a Torsen T2R posi. What is the best gear oil for this posi/car/gear setup?

 

[mdv]

Check out Amsoil, Redline and Specialty Formulations if you want the best stuff.

 

[VaderSS]

Torsens have their own fluid requirements, as opposed to the ring gear, as far as lubrication/protection and T2/T2Rs can safely be run in ATF and thicker fluids.

AA Torsen's bias("lock-up") is fluid dependent. The thinner the fluid, the greater the bias, so you want to run the thinnest fluid that still meets the ring-gear specs, in this case, a 90 grade GL4 gear oil.

Limited slip additives also reducues the bias, and are not needed in the T2. In some cases, a noise may be heard in turns and friction modifier can be used to eliminate that noise, but the noise is purely nuisance, not a wear issue, and does not happen in most cases. I'm not sure if LSD additive is needed for T2Rs. I'd contact Torsen directly or just run a synthetic with LSD additives premixed. Almost all synthetic gear oils(with exceptions below) have LSD additive premixed.

My personal favorite is Specialty Formulation's HDS-5. The default has limited slip additive in the mix, but you can request that they not put it in.

Other favorites are Redline 75W90NS or NEO 75W90EP. These do not have limited slip additive. The LSD versions are Redline 75W90 and NEO 75W90HD

 

[BMWR1150GS]

I have a question regarding use of molybdenum disulfide in gear oil.

I use synthetic 75W-140 GL-5 gear oil in my BMW boxer motorcycle transmission and final drive. For those of you not familiar with this arrangement, the transmission and final drive have separate, dedicated reservoirs. The clutch is dry, similar to an automotive clutch arrangement,

BMW recommends 80W-90 or 90 GL-5 gear oil but sells the 75W-140 GL-5 product under their badge as their premium gear oil (packaged by Golden Spectro).

I use it with added molly (10%) to quiet the gears, reduce heat and friction and help extend seal life. I have experienced improved shifting over the miles.

Also, I have no issues with failures in either of these systems although there are horror stories regarding failure of the crown wheel bearing due to the cage failure and the balls wadding up usually causing additional damage.

There are those at other motorcycle websites who claim that messing with perfectly good gear oil by the addition of moly is unwise.

I continue to use moly as an additive for my gear oil.

Also, does anybody know how much moly is in Mobil 1 15W-50 EP GC? I use that in the engine and understand that M1 in this grade has higher than average moly content.

Any comments would be welcome and appreciated.