Transmission fluid flushes are more expensive than transmission fluid changes, according to L.D. Automotive. While the flush removes more of the old fluid and debris from the transmission, it can damage transmission seals and valves.
Before scheduling a transmission flush on a vehicle, L.D. Automotive recommends checking the owner's manual. Manufacturers normally recommend a flush every 30,000 to 100,000 miles. Having a flush more often increases the chances of damaging the transmission. Some manufacturers recommend a transmission fluid change for an older car with high mileage. An inspection by a certified automobile mechanic is recommended before choosing between a flush and a change.