Joel, Why? The automatic transmission fluid should be able to make it 30,000 to 50,000 miles in stop and go service before a change and that was with the original Dexron. Bob In a message dated 5/16/2012 8:01:44 P.M. Eastern Daylight Time, joel at joelsplace.com writes: Of course I change my transmission fluid when I change my oil too. Joel McGregor