Torsen Differential oil

[markffrj]

Hi guys,

Is there a maintenance interval for the chenge of the Torsen differential oil?
I asked my local Audi dealer, and they told that the oil is lifetime, but there is no chance that anm oil keep his characteristics over the time.
My car is 2014, with 6 years on road i think that it´s close to the time to change the oil...

Someone could give me a light abiout this theme?

[Hy Octane]

Who's lifetime, yours or the cars? Change away..

[markffrj]

The audi dealer told that the oil is lifetime, but i believe it´s a dumb assumption, in order to keep my differential healthy, i will make the change..

[eskimo0101]

When they say it's a "lifetime" fluid what they really mean is the lifetime of the WARRANTY. They really only care that the oil holds up long enough to protect the parts while Audi is paying the bill to replace them. That the oil failed and killed your diff when the repair will be coming out of your pocket doesn't matter to manufacturers. They get to market "low cost of ownership" with all these things that never need changing and as a bonus the shop makes money replacing parts that wouldn't have failed with a regular fluid change.

At least Audi still has drain plugs. My wife's old Mazda CX-9 had a transfer cased filled with that magic "lifetime" fluid but you couldn't get any dealer or most indy shops to replace it because you had to use a suction pump to suck it out of the fill plug. And of course the CX-9 forum was full of posts with blown transfer cases outside of the warranty coverage.

[markffrj]

Thank you, it was exactly what i was thinking, going to schedule the differential oil change in the next month.

[MacFady]

Chime in OP if you need any info on oil spec etc. but I think there is a DIY on the site. I always considered it meant "lifetime of transmission" but I read somewhere that in the US manufacturers can legally refer to it as "lifetime" fluid if it is good for 100k.

[findalex]

If anyone has found an approved alternative to G 055 145 A2, the torsen oil, please let us know. I don't want to pay $100+ for a liter.

My research has led to down the path of:

1. G 055 145 A2 = Castrol SAF-AG4 Q
2. SAF-AG4 Q = SAF AG4 + 4% friction modifier (Sturaco 1992 KS additive)
3. Sturaco 1992 KS additive = Sturaco 7098 (does NOT equal Sturaco 7098 LO)
4. Sturaco 7099 = Sturaco 7098 + blue dye
5. Sturaco 7099 = Ford C8AZ-19B546-A = Ford XL-3 friction modifier

Conclusion:

1) you can use 75W-90 with 4% Ford XL-3
2) I've spent too much of my life on this
3) You could probably just use Valvoline SynPower 75W-90 and be completely fine since it already has friction modifiers (https://www.carid.com/images/valvoline/pdf/synpower-gear-oil.pdf)

If anyone thinks it's wrong, please share what you know.

Thanks!

Alex

[Dippy]

For reference the Audi service interval for that oil change on a B8 RS5 is 19K.

[kunschner]

1. G 055 145 A2 = Castrol SAF-AG4 Q
2. SAF-AG4 Q = SAF AG4 + 4% friction modifier (Sturaco 1992 KS additive)
3. Sturaco 1992 KS additive = Sturaco 7098 (does NOT equal Sturaco 7098 LO)
4. Sturaco 7099 = Sturaco 7098 + blue dye
5. Sturaco 7099 = Ford C8AZ-19B546-A = Ford XL-3 friction modifier

Conclusion:

1) you can use 75W-90 with 4% Ford XL-3
2) I've spent too much of my life on this
3) You could probably just use Valvoline SynPower 75W-90 and be completely fine since it already has friction modifiers (https://www.carid.com/images/valvoline/pdf/synpower-gear-oil.pdf)


This is exactly the process I was going through to find an alternative for my A4 B6 Trans Code 01V Centre Diff which apparently calls for that fluid.
From my understanding, the FM was added for NVH reasons, and as found on the Torsen website they do say that manufacturers add FMs to deal with NVH and since wear is essentially a byproduct of NVH (via friction, vibration, impact, etc.) then in that regard it would follow that FMs also reduce wear on components. However in other statements they say there's no evidence to be certain of that (that however is from 2003).

I literally just found a Ravenol fluid with the G 055 145 A2 spec HERE (https://www.blauparts.com/ravenol-toren-differential-gear-oil-awd-tor-1l.html)
Contains 4% Friction Modifier.
However I already went by the Ford dealer and got the XL-3. Thanks for doing the leg work though, I believe your conclusion is correct.

[hahnmgh63]

Any good quality synthetic gear oil (75w-90 or 75w-85)+ friction modifer...or many manufacturers sell a version of their gear oil with the modifer already added. I use Redline 75w-85, probably one of the best synthetics out there.

[MyDimeIsUp]

Reviving this thread. I've replaced ALL fluids on my car except for the center diff. I'm replacing my tranny mount due to a vibration at idle while in gear (I did motor mounts 2 months ago so it has to be tranny mounts) and since I'm taking the X-brace off, I figured I'd do my center diff fluid. I'm gonna pick up some C8AZ-19B546-A XL-3 friction modifier from a local Ford dealership but am wondering which 75W-90 should I pick up from my local AutoZone/PepBoys to mix with the XL-3? And just to confirm I asked this before in another thread but I can't remember, if I have 1L of 75W-90 I should pour out 960mL (96%) of 75W-90 and mix it with 40mL (4%) of XL-3 friction modifier, correct?

Thanks all

[findalex]

if you can find a gear oil without friction modifiers, then it's preferred since you're adding your own. i think everything sold at autozone / pepboys already has FM added. I think liqui moly makes one: https://www.liqui-moly.com/en/fully-synthetic-hypoid-gear-oil-gl4-5-sae-75w-90-p004272.html#tab-label-description-title

[hahnmgh63]

I've been using Redline 75w90 in my Audi's center Diff for 30yrs. Just noticed that Redline now recommends 75w85. The Redline does have friction modifiers which is recommended for the center Diff.

[cuerna]

On the ravenol website they stated than their oil is better than OEM G055146A2 oil.