Changing gearbox on a Fairmont

Carmakers claim that you don't need to change the fluid or service the auto trans for "life", but what "life" means is anybody's guess.  Auto trans service specialists strongly suggest that the fluid be changed as often as every 20,000 km, much as it used to be. It's more critical if you are towing regularly, but 40,000 km on a car that is being driven normally would be a good guide to when you should consider having the fluid changed.