[Schurkey]

Originally Posted by geeteeohguy

I've used Dexron, then Dexron II, then Dexron III, now it's called Mercon as the Dexron ATF's are all obsolete. Anyway, I've always used GM spec ATF in mine for the past 30 years with no issues. I even have the original pump and gearbox on my '67 with 242,000 miles on the clock. The main trick is to have clean fluid and to have enough of it.

Originally Posted by David Jones

I found it fairly strange that Power Steering Services would simply state that you needed to use whatever the mfg recommended and let it go at that.

Because it doesn't make a lot of difference, and they're too lazy to provide detailed recommendations.

Do keep in mind that ATF has "evolved" over the years, it's getting thinner (lower viscosity) and it has increasing amounts of friction modifier to condition the wet clutches and bands in an automatic transmission, As it becomes more specialized for AT use, it may have become less suitable for PS use.

Given a choice, I'd happily use whatever aftermarket ps fluid happened to be "on sale" at my local parts house in every vehicle I own EXCEPT my Trailblazer--the power steering was noisy as hell in cold weather until I installed the "special" GM cold climate PS fluid (at $16 per PINT!) When I flush that one some years from now, I'm going to try ordinary aftermarket PS fluid, but if I have trouble (noise in winter)...it'll be back to the expensive GM stuff again.