When I replaced the factory fluid in the transmission and rear diff at 38K miles, the old diff oil was a little grey and I could see the shimmer of brass in the transmission drain so I know it made a difference. The shifting also improved dramatically.

Today I drained the Redline MTL from the tranny and replaced it with Amsoil MTL. The old stuff came out looking just as clear and clean as it went in almost 100,000 miles ago. Hardly a shimmer of brass anywhere. The rear diff was also pretty, and the Schaeffer's 293A Supreme 75W90 came out still smelling great. The magnet didn't have any junk on it, and there were no signs of water contamination. The front differential drain (still factory) was grey, and the magnet was covered in fine metal shavings. I'm certain I made a bit of difference with the front diff change, but I'm beginning to wonder if I didn't waste a bunch of money on the rear diff and transmission fluid.

Anybody here ever do oil analysis on your transmission or differential fluids?

 

Crap...this was supposed to go in the 03-07 Engine and Drivetrain forum...any mods help me out here?

I guess that last drink was one too many