[T3] Gearlube question

Jim Adney jadney at vwtype3.org
Tue Apr 24 18:14:29 PDT 2012

On 24 Apr 2012 at 19:53, Bobsnotch at aol.com wrote:

> A few years ago, Jim told us (as does Bentley) that we need to use GL4  in 
> the MT, and GL5 in the final drive of the AT. But what do we use now, as all 
>  I can find is GL4,GL5 in the same bottle, or just GL5 all by itself? I'm 
> wanting  to change the MT trans oil, and want to make sure I use the correct 
> stuff.  In the Bentley, they also call out a Mil spec oil, but, while the 
> numbers are  the same, the suffix letter is different. VW wants it to be a 
> "B", while the  jugs have either C or D on them. Is this still the same, or is 
> it different too.  Thanks for the help.  

The original spec was MIL-L 2105B, but that got superceeded by C and 
then D. Now I'm told that the 2105 spec is dead, so we're just 
looking for GL-4. I have the remains of a Pennzoil 5 gallon bucket in 
my garage, but I don't know if I can still buy more. Sounds like 
inquiring at NAPA is the way to go for most of us.

The multigrade GL-4/GL-5 is troubling, because our MTs don't like GL-
5, even though that's what the AT final drive requires. It's possible 
that the dual rating stuff would be fine in our MTs, but I don't 
know. As I understand it, the GL-5 is better for the hypoid gears in 
the AT differential and would be better for the MT differential, too, 
but it reacts poorly with the brass syncros in our MTs. Since our MT 
is a combination tranny/differential, with no separation between the 
two, we have to pick a lubricant that is compatable with both.

The AT is different, in that there is ATF in the tranny part and GL-5 
in the differential, with a seal in between, to keep the 2 fluids 
separate. So the AT differential can use the GL-5.

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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