Depending on the manufacturer of the vehicle, drivers should get the automatic transmission serviced regularly at intervals ranging from 30,000 miles to 150,000 miles. Each vehicle manufacturer recommends different intervals for time or mileage between services. The most basic transmission service is a fluid flush and filter change.
Most vehicles, under normal driving conditions, should have the transmission flushed at least every two years or 30,000 miles. More strenuous driving conditions, such as frequent stop-and-go traffic, towing, off-road driving or racing puts additional strain on an automatic transmission. If a vehicle is used in those types of driving conditions, the transmission should be serviced more frequently.