Rear Axle: Rear Transaxle Oil Spec.

[Greg Andrade]

I've drained the oil out of my "Twin-Traction" (posi-traction) rear end.
This rearend was not original to our Wagonaire
We know it's an Avanti becasue the brake shoe spec tells us so - year unknown.
The shop manual says use either A or B for oil in this unit;
A. "Studebaker Twin Traction Lubricant = ?
B. 90W / API-GL4
Or
C. Do I use 90W GS-1 old school type rear end oil?
Any insights? thanks - g

[Mike Van Veghten]

Transaxle ?

Did Stude make a "transaxle" ? Might have been interesting..
Just an axle as far as I know...

Mike

[Bud]

Any good 80W-90 conventional or 75W-90 synthetic gear lube will be suitable for your TT differential. Try to buy an oil that has a limited slip additive already added or you may have to use an additive to keep the clutches from chattering. I use Amsoil Severe Gear 75W-90 synthetic gear lube in my cars and in my 2010 Silverado and I'm happy with the results. Bud

[Greg Andrade]

Thank you Bud for your insight - we subsequently discovered that our rear end was ordered with our wagon and is an original '63 TT posi- Now we can use your insight and get the correct oil so thanks again - g

[StudeRich]

Greg, you need GL-5 Extreme Pressure (EP) Gear Lube for all Differentials.

For a complete drain & "Fill" on Twin Traction Diffs. it is recommended to add the 4 Oz. bottle of GM, or Dodge/Jeep Friction Modifier, Limited Slip additive to the Oil or it's aftermarket "replacement".

[Dan Timberlake]

The result of not using oil with suitable LSD additives can be chatter due to clutch stick-slip going around corners. Back in the 70s A buddy was all set to take the rear axle out of his beloved Alfa Romeo because it made horrible metallic noises going around slow speed corners. We drained the ancient oil, refilled with Valvoline HP and the noise was instantly gone.

[over50]

Search for previous thread discussions on gear lubes for TT differentials. I use Valvoline Syn Power Full Synthetic for Limited Slip. Some people like to put the GM limited slip additive in regular gear oil.