Normal wear of the transmission produces metal shavings in the fluid. While this is not a problem, it indicates it is time to change the fluid, according to AutoZone. Failure to perform this maintenance task according to schedule allows these shavings to increase transmission wear, leading to early failure.
Automatic transmission vehicles use automatic transmission fluid, while manual transmissions use a variety of oils and other fluids. When changing the fluid, the owner's manual provides information on the type to use. It is essential to follow the manufacturer's recommendation, as certain fluids are not compatible with others.
Manufacturers offer different maintenance schedules for transmissions. Typical service schedules for an automatic transmission include oil changes every 60,000 to 100,000 miles, while manual transmissions require changes every 30,000 to 60,000 miles. If the vehicle operates under high heat or dusty conditions or tows trailers, fluids require more frequent changes.
Manufacturers recommend that owners check fluid levels regularly between changes, adding more as necessary. Unfortunately, there are few noticeable signs of low transmission fluid until damage occurs to the transmission. Cars do not burn transmission fluid, so a low level is almost always an indication of a fluid leak. A red oily substance under the vehicle is usually leaking from the transmission.