Gear lube for 4kq

Kneale Brownson knotnook at
Sun Jun 17 11:34:48 EDT 2001

As I've understood previous postings on the subject,  Audi specifies GL4 
for trannies to provide a protection for the synchronizers that GL5 doesn't 
provide.  GL5 goes in final drives because there are no synchronizers 
there.  If you want more technical explanations, there are lots and lots of 
postings on this subject available through a Google search on the website.

At 09:57 PM 06/16/2001 -0400, Andrew Buc wrote:

>According to the Bentley, the 4kq transmission takes SAE 80W or 80W/90,
>GL4, and the rear diff takes SAE 90, GL5. I've heard good things about
>Swepco gear lube (, and today I spoke to their local
>distributor. From what I could see on the website, it's supposed to be
>a real premium product, w/price to match, even though it isn't
>synthetic. The closest grade they make is 80W/90, GL5, and I wondered
>if this would be OK. The guy said it would give at least as much
>protection as SAE 90. As to GL4 vs. GL5, he said the GL5 rating
>supersedes the GL4 and is better. I got the impression that this was
>analagous to being able to use, say, SG-rated engine oil (I don't know
>offhand what rating they're up to these days) in an older car that
>calls for SF or lower. But I didn't explicitly pursue this line of
>Pending getting feedback from the list, I checked Castrol's website,
>figuring that they'd have a wide range of weights and grades. Well,
>they have both GL4 and GL5, but no SAE 90--closest is 80W/90. If I go
>with Castrol (Swepco is pretty spendy), will 80W/90 be OK in the rear
>diff? Thanks!

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