My new 4x4 xlt has 9000 mi on it-no problems yet. I take it up to the Sierra's often sea level to 9000 ft 700 mile round trip. How often should I have the tranny fluid changed and any suggestion on how to extend the tanny life?

 

Follow the maintenance schedule for severe service. It's in your owner's manual.

For best life I recommend a synthetic ATF.

Mark