owners manual reccomends changing tranny fluid at 100,000 miles. You reccomend every 30,000. Who to believe?
Automatic transmission fluid change on 2007 Pontiac Vibe
The manufacturer recommended interval is the minimum requirement, if you look it might have a "severe service" interval that will indicate replacement more often. 100,000 is a long time to go without replacing the fluid, I wouldn't go over 60k, 30k is fairly normal.