My vehicle manufacturer says that the automatic transmission fluid doesnt need changing. Change or leave it alone?
Manufacturers may feel the odds of problems from improper service are greater than the odds of problems from no service at all. The wrong fluid, not enough or too much fluid, the wrong filter or one not properly installed will ruin a transmission quickly. I think their recommendation are based on this and a supposed service life of 100K miles. With proper service, any given transmission will last longer. Lack of service may cause failure from plugged filters, debris and depleted fluid. A proper service can never hurt the vehicle and may very well extend transmission life, especially if the vehicle is driven beyond 100K miles. For much more on proper transmission service, see our article Transmissions and proper service.
