VW/Audi G-052-145-S2

[MolaKule]

VW/Audi specs this product for rear differentials and transfer cases. Supposedly it is a 75W90, but Redline recommends their MT-90 product, not their regular 75W90. Their rationale is that Audi uses a "low offset rear final driver gear set" and this setup does not require GL-5.

This makes sense for a low offset differential.

If the transfer case and differential all require a 75W90 then it seems that the MT-90 would suffice. I do know Redline's MT-90 has a high level of AW chemistry.

 

[TiGeo]

I run Redline MT90 75-90 in the bevel box and r. diff on my Sportwagen and the front diff (?) on my W8 Passat. R. diff on Passat takes GL5 75-90.

 

[Vercingetorix]

You’re buying 2.5+ quarts. That means three bottles, one for each of the three boxes. May as well buy the correct fluid for each.

 

[930.engineering]

Either way, GL-4. I've checked half a dozen "oil selector" pages and none of them say to use a dedicated GL-5, at best the GL-4/5. Usually just GL-4. Even if some were wrong, they can't all be wrong.
Regarding Liquimoly, some online sellers recommend their older GL-5 spec "gear oil" for G-052-145, in the blue and black bottle. However, I see they're recommending MTF 5400 now for this, which is GL-4. Go figure.

That's what Ravenol is recommending for G 052 145 (VSG SAE 75W-90 > API GL-4 & GL-5):

https://www.ravenol.de/en/properties/empfehlung/vw-g-052-145-a2

This is what Castrol Germany recommends for G 052 145 (Transmax Axle Long Life 75W-90 > GL-5 only):

https://www.castrol.com/de_de/germany/home/product-finder.html?page=product&id=469698

Castrol is an actual "OEM", because of this I'd tend to follow their recommendations.