I changed it 35K miles ago. But....That was 12 years ago......Does the Auto Trac II go bad over time or is it just mostly linked to mileage? Envoy is an every once in awhile weekend driver. Thanks for any input.
Hmm. I know there's a mileage limit, but I personally don't know of a time limit, like there is for motor oil (which is generally 1yr, even if the mileage limit hasn't been met. That's because motor oil gets acidic, over time).
That being said... there's no penalty (except financial) for over-maintaining a vehicle.
If it's bothering you (and especially if you make regular use of the 4WD), change it out. It probably is bothering you, if you went to the trouble to post / ask, right?
Like they said, if there is serious moisture intrusion, change. Don't worry about time.
Different pile but same sht, years ago I emailed Cummins engineering about condemnation limits on engine oil. They graciously provided me with all sorts of info. Oil shear, wear metal trending, soot and oxidation are items to condemn an oil, no where did they mention time.