What is the duty cycle of transmission fluid for each unit?
In normal use, the automatic transmission fluid should never need to be replaced unless the transmission is serviced. Fluid level should be checked periodically and topped off with the correct type. Under severe conditions (taxi use – that severe) the transmission fluid and filter should be replaced every 15,000 miles. For most of us it seems that something in between, say every 50,000 miles, would be prudent. The manual transmission fluid duty cycle is the life of the car. Even under racing conditions, there is no evidence that it needs to be replaced more frequently. Either fluid should be replaced if water or other contaminants get into the unit.
