Brozee

Also was it this red line? Much cheaper on amazon:
http://www.amazon.com/Red-Line-57904...7838873&sr=8-1

or this (i don't think it's this one because this is for non slip diff)
http://www.amazon.com/Red-Line-58304...7838873&sr=8-3

mishar

As I mentioned earlier some transmissions have combined oil in the front and middle differential. In that case it has to be same oil.

Unfortunately I couldn't find which ones has combined and which separated oil systems. All those letters, Bentley, ELSA and only think I can say is that combined system has two pipes on the right side connecting front and middle differential and the other doesn't. Combined system also has oil cooler and it seams that the other doesn't.

Another thing bothers me. I didn't notice anything about draining any of those oils. Only topping. Can't remember if I saw some plugs that may be for that purpose. I remember oil cooler but not sure about pipes.

I think that clarification is necessary before any action. Including that extra liter of oil.

bmwm750

I'm using Red Line 75W90, not 75W90NS (which is for transmissions and transaxles without a limited slip). Audi says FM booster should be used in the center and rear diff, so I don't think you want the NS fluid.

Like I said, I'm using the "super exotic center diff fluid" in the center, and Red Line in the front/ rear.

From what I have from Audi, the 6HP as installed in the A8 has separate fluid for the center and front diff.

I'll know much more next week, after I do all this.

Brozee

Patiently waiting for your update

bmwm750

I got extended at work, so just got home today, so this will be getting done later in the week. Update by the weekend, I promise!

bmwm750

Well, turns out when I ordered Red Line stuff today, they actually recommend MT-90 for the diffs, not 75W90.

Interesting......

Brozee

Really? That's odd. You should call up a dealer that has done it before and see what they can say. Granted you don't talk to one of the robot service advisors "only OEM fluid blah blah"

The 75W90 is a GL-5 oil. The MT-90 75W90 is a GL-4. Maybe the A8 needs the GL-4 oil.... granted the A8 doesn't have hypoid gears?

bmwm750

I've got a bunch of MT90 laying around from a transmission service I did a year ago, and just ordered a few quarts of 75W90, and I'm going to call Red Line tomorrow and have a chat with them.

Does anyone know if the factory fluid is GL-4 or GL-5 rated?

I have NEVER put GL-4 into a separate differential, so I find it very odd that they recommend the MT90.

snapdragon

G 052 145 A2 = GL5
Factory fill was Castrol SAFXO which is no longer made.
New oil in Audi dealers from late 2011, part number stays the same.

bmwm750

Sounds like Red Line 75W90 it is. Thank you for the clarification.