Although the function of the transmission oil and filter are similar to the engine oil and oil filter they perform their jobs differently. Most of today’s vehicles require five to seven quarts of motor oil. The same vehicle will require 12-15 quarts of transmission oil.
Transmission oil operates in a much hotter environment than motor oil. A function of the oil is to disperse heat and to carry the heat away from the source. It is also responsible for carrying contaminants in the transmission to the filter and depositing them in the filter.
The contaminants are created by heat. As the transmission heats up, so does the fluid, leaving behind a carbon buildup on the moving parts of the transmission that need to be cleaned and carried to the filter. Because transmission oil is a high viscosity oil, as it heats up, it also expands. This means the filter has to be able accept the fluid and filter the fluid in various degrees of oil thickness. Who knew so much was going on to ensure that when you put your vehicle in gear it performs so seamlessly?
Most modern transmissions are being filled with “lifetime” fluids. This kind of transmission fluid typically doesn’t require service until the vehicle has reached at least 100,000 miles. However, defer to your owners manual for the final say.
The above was written by Lauren Henderson and was published by GoDrive magazine Winter 2015