Front Differential Oil Help

[Willënskraft]

Hi AZ,

I'm having some confusion and need help selecting the front and rear differential oils. From my understanding is that the front diff and transmission share the same oil. While the rear uses another oil seperately.

So I searched ECS for the front diff oil and found this one and this one not sure what the difference is besides prices lol. Are they both compatible with a 2002 A4 1.8T Quattro?

[diagnosticator]

Front diff: SAE 75W90 Synthetic Gear Oil. 0.8l.

Center diff: Use synthetic gear oil, SAE 75W90, 0.8l

Rear diff final drive: Use synthetic gear oil GL 5 SAE 90 for 01R final drive. 1.5l

Front and center diffs use the same SAE 75W90 synthetic gear oil.

[Luxus Panzer]

I am still considering putting SAE 75W90 Synthetic Gear Oil in my read diff (6 Sp MT)

http://www.audizine.com/forum/showth...6#post11661766

[SJorge3442]

I am still considering putting SAE 75W90 Synthetic Gear Oil in my read diff (6 Sp MT)

http://www.audizine.com/forum/showth...6#post11661766

Plenty of people recommend the Fuchs titan sintofluid 75W-80 for both the trans and the rear, including Scotty over at Advanced Automotion. I've had the oil sitting on the shelf since January. Just havent gotten to it. Been too busy with other peoples cars.

[Luxus Panzer]

Plenty of people recommend the Fuchs titan sintofluid 75W-80 for both the trans and the rear, including Scotty over at Advanced Automotion. I've had the oil sitting on the shelf since January. Just havent gotten to it. Been too busy with other peoples cars.

Read carefully, my above post denotes Fuchs titan sintofluid 75W-90 with regards to both 5 and 6 speed MT

Old Guy - "The Sintopoid is more than just a differential gear oil. It doesn't have the sulfur compounds, is fully synthetic and rated for both GL4 and GL5 applications. Clicky click So yes it is safe to use in a manual transmission. "

[Willënskraft]

Any difference between G055145A2 and G052145S2?



G055145A2




Vs.


G052145S2

[Willënskraft]

Also is there a center differential?

[Luxus Panzer]

Have a read of my post/link above...

why not just go with Fuchs sintofluid 75w90 in everything (front and rear)

It doesn't have sulfur compounds, is fully synthetic and rated for both GL4 and GL5 applications

[diagnosticator]

I am still considering putting SAE 75W90 Synthetic Gear Oil in my read diff (6 Sp MT)

http://www.audizine.com/forum/showth...6#post11661766

Do not use SAE 75W90 gear oil in the rear diff. It must be filled with SAE 90 GL 5 because the rear diff uses hypoid gearing that is what the heavier viscosity straight 90 wt and the GL 5 specs address.

[Luxus Panzer]

Do not use SAE 75W90 gear oil in the rear diff. It must be filled with SAE 90 GL 5 because the rear diff uses hypoid gearing that is what the heavier viscosity straight 90 wt and the GL 5 specs address.

even if the 75w90 in question is Fuchs sintofluid, which meets both GL4 AND GL5 specs??

[diagnosticator]

even if the 75w90 in question is Fuchs sintofluid, which meets both GL4 AND GL5 specs??

The crucial difference is the multi viscosity 75W90 compared to the straight viscosity 90 wt, The multi viscosity lube oil can shear down and become thinner that 90 wt overtime. The straight 90 wt GL 5 gear oils are a lot more stable and resist shear viscosity loss. The rear diff needs the higher viscosity of the straight 90 wt oil and the extreme pressure additives of the GL 5 Spec.

[diagnosticator]

Also is there a center differential?

Yes, as noted in the fluid fill specs.

[Luxus Panzer]

The crucial difference is the multi viscosity 75W90 compared to the straight viscosity 90 wt, The multi viscosity lube oil can shear down and become thinner that 90 wt overtime. The straight 90 wt GL 5 gear oils are a lot more stable and resist shear viscosity loss. The rear diff needs the higher viscosity of the straight 90 wt oil and the extreme pressure additives of the GL 5 Spec.

Great, now I am super confused.

My linked thread went back and forth and eventually settled on that it was good for both the 6sp MT and rear diff. Now this thread is telling me no.

Ugh... and I have $100 worth of this fluid sitting in a jug in my garage :(