When should you perform a transmission fluid replacement on the 2004 toyota highlander V6?

Depends on how you work the car and how long you plan on keeping it.

If you plan on keeping it forever, I'd flush and renew the fluid every 50,000 miles. If you plan on getting rid of it before 100,000 miles, you probably don't have to touch it. If you work it very hard, I'd flush and renew the fluid every 30,000 miles.

Ken

On Tue, 09 May 2006 08:24:56 -0700, Ken Shelton found these unused words floating about:

Doesn't that also depend upon the climat? Time in desert heat 'supposedly' shortens the life of the fluid as it runs some 10* or more hotter than in the 'north'.

Yes, but modern ATFs are made of better ingredients than older formulations. GM's latest Dexron version, Dexron-III(H), is recommended for a change under severe service at 100,000 miles. I think that might be too long, but all the modern fluids are better.

Ken