4L60-E Automatic Transmission

Fluid level should be checked at every oil change. Frequency of change for transmission fluid is dependent on the type of driving conditions in which the vehicle is used. If the transmission is subjected to severe service such as: use in heavy city traffic when the outside temperature regularly reaches 90°F, use in very hilly or mountainous areas, commercial use such as taxi or delivery service, the fluid should be change every 15,000 miles for vehicles under 8,600 GVWR or every 12,000 for vehicles over 8,600 GVWR. Otherwise, change fluid every 30,000 miles for vehicles under 8,600 miles GVWR or every 24,000 miles for vehicles over 8,600 miles GVWR.