Fluid changes - OEM vs aftermarket

I'm running Red Line 75W90 in the rear diff, no issues and it does meet the GM spec for this car, and less expensive than the grape stuff from the dealer. I trust the other Red Line fluids too, have used them in various vehicles, you can order them on Amazon.

I'm the one that used the Redline fluid in the trans. I don't believe the fluid caused the whining- everything is still normal, and the whining went away as the weather got nicer (warmer). Heck, it's possible that the fluid just needed to break down a bit. I'm not concerned. Redline is also going into my Z06's transmission soon, very popular among Corvette owners.

That being said, if I were to do it again, I'd stick to OEM fluid for something as intrinsic as a Cadillac transmission. I can't say for sure whether the whining was an existing issue or not, as it was my first winter with the car.

I also recently changed my front/rear diff and t-case oils with Mobil 1 stuff. No issues thus far.

Thanks for the replies. I forgot about the rear differential fluid, will have to add that to the list. Any comment on brake fluid or anti-freeze?

I just stick with an off the shelf dot 3/4 brake fluid. Unless if you have a V that you road race, no reason to spend extra on a better brake fluid.

People have varying opinions on coolant. Some switch to green, others stay with dexcool. IMO dexcool is fine as long as you change it at a certain interval (no longer than 50k if I remember right?) I'd rather not go through the hassle of flushing it out to change to green coolant because it's hard to tell whether you flushed it well enough- dexcool and regular coolant shouldn't be mixed.

Boat said:

I just stick with an off the shelf dot 3/4 brake fluid. Unless if you have a V that you road race, no reason to spend extra on a better brake fluid. People have varying opinions on coolant. Some switch to green, others stay with dexcool. IMO dexcool is fine as long as you change it at a certain interval (no longer than 50k if I remember right?) I'd rather not go through the hassle of flushing it out to change to green coolant because it's hard to tell whether you flushed it well enough- dexcool and regular coolant shouldn't be mixed.

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Dex change interval is 5 year 100k. I wouldn't let it go that long though. Cheap insurance and any monkey can do a drain and fill on the rad every 75k. A full system flush is impossible without proper equipment.