Kyle:

Thanks for the info!  Your explanation of GL-5 for the front
differential makes sense.  Redline also cautions not to use GL-4 in a
rear wheel differential which requires a GL-5 lubricant.  BUT...Bently
clearly says at page 39.42 that the front diff. lubricant specs is for
"Gear oil GL-4 SAE 80."

I called Redline and spoke with their tech.  He said that his specs call
for Redline 75/90, which is a GL-5, in the front differential.
Redline reccomends MT 90 (a GL-4) for the transaxel, or MTL in colder
climates...but both would fall within specs and would outperform regular
gear oil.

Thanks again, Kyle, for bringing this to my attention.

vwmaster@volks-motorsports.com wrote:

> Steve,
>
>   I saw your post and wanted to let you know what german Transaxle
> said
> on this topic when we got a Viscus Coupler for them.
>
>   They instructed us to use GL-5 in the front diff and to use GL-4 in
> the Trans.
>
>   To my understanding the GL-4 has a property in it that helps to
> lubricate the Syncros in a Transmission .
>
>   A front diff has no Gear Clusters it only need the DIFF lubricated.
>
>   In the warranty sheets from German Trans it said using anything
> other
> than GL-5 in the front diff will void warranty.
>
>   Just wanted to pass on this info.
>
>   FYI, I do belive that you need to drop the sub frame to drain the
> trans oil easily.
>
>   The tool is a 17mm Allen and I have a fairly inexpensive one that I
> sell, $4.95.
>
>   Just wanted to pass on my GL-4/GL-5 info.
>
>   Kyle
> --
>
>   Kyle Wade  (408) 426-1431 OR  (408) 429-9424
>   Keeper of the Volks-Motorsports page
>   Home Page - http://www.volks-motorsports.com
>   ICQ # 3882975