Differential fluid frustration
06-10-2018, 10:28 AM
#1
AudiWorld Senior Member
Thread Starter
Differential fluid frustration
I am getting really discouraged with trying to figure out what kind of diff oil to buy. I want to get Redline fluid. But it says it’s for limited slip rear diff. I have no idea if I have that. I have an 06 A6 3.2 Quattro. It says that fluid can be used for Transmissions also so it really confuses me. I also see some recommended fluids that are 75w110. But I probably need 75w90 right?
I have the dealer part numbers for their fluid but the Redline doesn’t cross reference with the dealer numbers.
Rear diff -G052-145-A1
Front - dealer said I can use same as rear or G052-145-S2
Transfer case/box - G055-145-A2
So that begs the question....if I can use the A1 in the front as well as the rear, does that also mean if I buy the S2 I can use it in the rear also? Or does only the A1 work in the rear? That can’t be the case because I’ve seen lots of posts from people saying they put the same fluid in both.
Also, for the transfer case fluid am I basically stuck with getting that $90 genuine Audi fluid? I have heard people who tried to put something other than that in it and had bad results.
I don’t need top of the line fluid but I don’t want the worse stuff either. I think Redline is good and not too expensive either and that’s why I want to get it. Anybody recommend Liqui Moly, Fuchs or Castrol?
I want to also replace the rear and front diff seals because I have fluid leaking from them and a person that I trust looked under there said I needed to replace my diff seals. I see lots of products for those also. I see Axle seals, diff seals, diff output shaft seals, etc. Am I looking for something called “Differential Seals”. Also not sure if the front and back takes the same part??
Someone please help me. I want to get this ordered and do it next weekend. I appreciate it.
I have the dealer part numbers for their fluid but the Redline doesn’t cross reference with the dealer numbers.
Rear diff -G052-145-A1
Front - dealer said I can use same as rear or G052-145-S2
Transfer case/box - G055-145-A2
So that begs the question....if I can use the A1 in the front as well as the rear, does that also mean if I buy the S2 I can use it in the rear also? Or does only the A1 work in the rear? That can’t be the case because I’ve seen lots of posts from people saying they put the same fluid in both.
Also, for the transfer case fluid am I basically stuck with getting that $90 genuine Audi fluid? I have heard people who tried to put something other than that in it and had bad results.
I don’t need top of the line fluid but I don’t want the worse stuff either. I think Redline is good and not too expensive either and that’s why I want to get it. Anybody recommend Liqui Moly, Fuchs or Castrol?
I want to also replace the rear and front diff seals because I have fluid leaking from them and a person that I trust looked under there said I needed to replace my diff seals. I see lots of products for those also. I see Axle seals, diff seals, diff output shaft seals, etc. Am I looking for something called “Differential Seals”. Also not sure if the front and back takes the same part??
Someone please help me. I want to get this ordered and do it next weekend. I appreciate it.
06-10-2018, 04:27 PM
#2
AudiWorld Member
I have had three 3.2 A6's. I have used amsoil fluids in all of them (trans, front/rear diff and transfer case). I have not had any problems. I'm not sure how the Redline fluids translate to the audi fluids but I'm sure you can find them with a search. If you go to the amsoil site and select lookup fluids for my car, then select the small link that says: switch to previous version. That will let you put in your year, make model and it will give you recommended fluids and capacities. there are many threads about changing all the driveline fluids. I can't help you on the differential gaskets/seals, sorry.
06-10-2018, 05:45 PM
#3
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The rear differential takes plain old 75W-90 gear oil. Any decent gear oil should be fine. The center differential takes special unicorn tears gear oil that costs a fortune and only take like half a quart to refill. (Audi Part G 055 145 A2) It's supposed to keep the center diff quiet. It doesn't work lol. Honestly, a good 75-90 would probably be fine for that. Our front/rear diffs are open (not limited slip) and uses the brakes (ABS module) to handle traction control. Limited slip additive likely won't cause any harm.
There's 3 seals on the rear differential so you really need to know which one is leaking. If it's in the input shaft, you unhook the drive shaft, slide the yoke out of the diff, pull the seal out and replace it. The output seals on either side I've never done so not sure the process to take them apart. Output shaft on the back of the center differential should be the same as the differential. It's generally a round seal, you can pull it out with a hook and gently tap a new one in with a hammer flat object. Good luck.
There's 3 seals on the rear differential so you really need to know which one is leaking. If it's in the input shaft, you unhook the drive shaft, slide the yoke out of the diff, pull the seal out and replace it. The output seals on either side I've never done so not sure the process to take them apart. Output shaft on the back of the center differential should be the same as the differential. It's generally a round seal, you can pull it out with a hook and gently tap a new one in with a hammer flat object. Good luck.
06-11-2018, 08:50 AM
#4
Like the others have said, front and rear are just regular gear oil and the center takes the special Audi juice.
I used Redline NS (for non-limited slip diffs) since we have a locking open diff.
I used Redline NS (for non-limited slip diffs) since we have a locking open diff.
06-11-2018, 11:02 AM
#5
When I did mine, documented here: https://www.audiworld.com/forums/a6-...-oils-2843310/
I used Redline SAE 75W-90 API GL-4 for the front and rear transfer case and for the middle I used the recommended Audi fluid, purchased from the dealership.
I used Redline SAE 75W-90 API GL-4 for the front and rear transfer case and for the middle I used the recommended Audi fluid, purchased from the dealership.
06-12-2018, 09:34 AM
#6
AudiWorld Senior Member
Thread Starter
I have had three 3.2 A6's. I have used amsoil fluids in all of them (trans, front/rear diff and transfer case). I have not had any problems. I'm not sure how the Redline fluids translate to the audi fluids but I'm sure you can find them with a search. If you go to the amsoil site and select lookup fluids for my car, then select the small link that says: switch to previous version. That will let you put in your year, make model and it will give you recommended fluids and capacities. there are many threads about changing all the driveline fluids. I can't help you on the differential gaskets/seals, sorry.
06-12-2018, 09:42 AM
#7
AudiWorld Senior Member
Thread Starter
The rear differential takes plain old 75W-90 gear oil. Any decent gear oil should be fine. The center differential takes special unicorn tears gear oil that costs a fortune and only take like half a quart to refill. (Audi Part G 055 145 A2) It's supposed to keep the center diff quiet. It doesn't work lol. Honestly, a good 75-90 would probably be fine for that. Our front/rear diffs are open (not limited slip) and uses the brakes (ABS module) to handle traction control. Limited slip additive likely won't cause any harm.
There's 3 seals on the rear differential so you really need to know which one is leaking. If it's in the input shaft, you unhook the drive shaft, slide the yoke out of the diff, pull the seal out and replace it. The output seals on either side I've never done so not sure the process to take them apart. Output shaft on the back of the center differential should be the same as the differential. It's generally a round seal, you can pull it out with a hook and gently tap a new one in with a hammer flat object. Good luck.
There's 3 seals on the rear differential so you really need to know which one is leaking. If it's in the input shaft, you unhook the drive shaft, slide the yoke out of the diff, pull the seal out and replace it. The output seals on either side I've never done so not sure the process to take them apart. Output shaft on the back of the center differential should be the same as the differential. It's generally a round seal, you can pull it out with a hook and gently tap a new one in with a hammer flat object. Good luck.
Great info. You say that the rear diff takes "plain old 75W-90" but you don't mention the front with that statement. Are you saying that the front takes a different kind than the back? I understand that I for the center (transfer case) I am gonna bite the bullet and get the unicorn tear gear oil.
You say that the front and rear are "open" and NOT limited slip..........yet the redline site shows the fluid that it recommends is the 75W-90 GL-5 and it says on the bottle that it is for "Hypoid Limited Slip Differentials". I have not idea what "hypoid" means but if this is the only fluid they recommend for my car, then this is the one I would think to use. No?
You are calling the 2 seals on the sides of the rear diff "output shaft" seals. Is that the same as "Axle seals"? I keep hearing different terms used. I am almost inclined to change them all because I am going to a shop with a lift and don't want to go back multiple times because it is about 45 min drive. I should have done a better job of diagnosing the leak when I had it in the air a few months ago. Ugh.
Thanks.
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06-12-2018, 09:58 AM
#9
AudiWorld Senior Member
Thread Starter
When I did mine, documented here: https://www.audiworld.com/forums/a6-...-oils-2843310/
I used Redline SAE 75W-90 API GL-4 for the front and rear transfer case and for the middle I used the recommended Audi fluid, purchased from the dealership.
I used Redline SAE 75W-90 API GL-4 for the front and rear transfer case and for the middle I used the recommended Audi fluid, purchased from the dealership.
I have read the thread numerous times that you posted. Is the 75w-90 GL-5 fluid just a newer version of the 75w-90 GL-4? Or do I need to go and find the GL-4? In my reply to SnowZach I point out that the redline site only has that 75W-90 for Hypoid limited slip differentials and that's what they recommend for my 06 A6 3.2 Quattro. Do I need to go and find the NS fluid that he is talking about?
Never thought this could be so complicated. Makes me want to just go and give the dealer $800 to do something that will cost me $150 and an hour of my time.
06-12-2018, 10:01 AM
#10
AudiWorld Senior Member
Thread Starter
You want this one, without the LS friction modifiers: https://www.amazon.com/Red-Line-Limi.../dp/B000CPI5Y6
Here's the 4 pack which is enough for the front and rear: https://www.amazon.com/Red-Line-75W9.../dp/B0041EG0KU
Here's the 4 pack which is enough for the front and rear: https://www.amazon.com/Red-Line-75W9.../dp/B0041EG0KU
There we go. Now we are talking. So what piece of info am I leaving out that is causing this NS fluid to NOT show up on any sites when I enter my car info. I am entering 2006, A6 3.2 Quattro. What makes my car need the NS but even the redline site says to use that other fluid (for hypoid limited slip diffs)? Thanks for your help man.