I just picked up a 09 Cadillac CTS-V, these cars have a heavy duty Getrag diff and are notorious for burning up factory fluid because of poor cooling and sometimes being under filled. My car has 40k on it. Even cars drained at 12k drop out black fluid.
The main forum for these V's are filled with some fairly intelligent people and there is a consensus on the forums to NOT use AMSOil in your diff. There have been repeated issues with noise afterwards from members who use AMSOil but no one has gotten into the "why" of this. The noise was always remedied by a change back to GM fluid. I'm glad I bothered to read their long thread because I was about to order some 75w90 Severe Gear.
No one has issues with Royal Purple, Red Line, M1. GM has two types of diff fluid and both are used by forum members without issues. The old grape scented stuff that you have to add limited slip additive too, and the newest fluid #88862624 that needs no additive. This: https://www.amazon.com/Genuine-88862624-Differential-Lubricant-Quart/dp/B00GTJD5RG
The link contains what seems to be the forum favorite. Though it is viewed as GM Secret Sauce Diff Fluid. "It's better, we just don't know why, you should use it because everyone else is using it." That is the gist of it.
In my opinion, considering all the issues people have had with diff whine from premature wear, bearing failures, burned fluid, etc. Maybe that GM fluid is not the best option. For the price of 2 quarts of GM 75w90 I can get buy 6 quarts of Mobil 1 LS 75w90. Probably would cover me for my full ownership period of 3-4 years.
Thoughts BITOG?
The main forum for these V's are filled with some fairly intelligent people and there is a consensus on the forums to NOT use AMSOil in your diff. There have been repeated issues with noise afterwards from members who use AMSOil but no one has gotten into the "why" of this. The noise was always remedied by a change back to GM fluid. I'm glad I bothered to read their long thread because I was about to order some 75w90 Severe Gear.
No one has issues with Royal Purple, Red Line, M1. GM has two types of diff fluid and both are used by forum members without issues. The old grape scented stuff that you have to add limited slip additive too, and the newest fluid #88862624 that needs no additive. This: https://www.amazon.com/Genuine-88862624-Differential-Lubricant-Quart/dp/B00GTJD5RG
The link contains what seems to be the forum favorite. Though it is viewed as GM Secret Sauce Diff Fluid. "It's better, we just don't know why, you should use it because everyone else is using it." That is the gist of it.
In my opinion, considering all the issues people have had with diff whine from premature wear, bearing failures, burned fluid, etc. Maybe that GM fluid is not the best option. For the price of 2 quarts of GM 75w90 I can get buy 6 quarts of Mobil 1 LS 75w90. Probably would cover me for my full ownership period of 3-4 years.
Thoughts BITOG?
