Transaxle lube for VW

[tspot100]

Hi, Glad i found this forum, very informative.
I have a stock 1968 VW beetle and am unsure which type of manual transaxle lube to use. The owners manual calls for an 80w hypoid type. Can't find it. I have read ad nauseum about the differences between gl-4 and gl-5 also the gl-5 MT-1.
What the heck???
The more I researched on the net, the more confused I became. Amsoil, Redline,swepco, etc??? Dino, synthetic ???
One site said the diff between gl-4 and gl-5 was EP additives. Some attack yellow metals in the case,some think the MT-1 designation of gl-5 cured that...
I'M SO CONFUSED!
Is there any consensus for my application?
Can anyone point me to a site which clarifies the issue?
Thanks in advance.

 

[unDummy]

Why worry? Use a dual rated fluid.

SpecialtyFormulations MTL-R
Redline 75w90NS
RoyalPurple Maxgear 75w90

I personally think that the 'damage' by GL5 fluids is overrated. I've used GL5 fluids in a bunch of manual trannies with no issues. I think that the important thing is to keep the fluid fresh. Since I usually fry clutches every 50k miles, my transmission fluid change happens at every clutch job. I had a tranny go 250k miles with Mobil-1 GL5 75w90. Even with a 1/4 million miles, that tranny shifted better than most new cars do today.

 

[mechtech]

GL4 had a less protection [Anti wear, extreme pressure additives]than GL5. GL5 is good for hypoid gears, that slide at the surface contact area.
GL4 had about 1/3 of the possible corrosive additives that GL5 had [sulfer based]. It was not void of them, however.
It takes some moisture, and a LOT of heat to get to be corrosive, however.
Modern Gl5 lubes are buffered and don't have this problem.
That said, I'd contact Specialty Formulations for a modern lube with great protection, and good shifting properties.
Often, a GL5 for differential use will not be good for shifting.