Fluid Change Intervals

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 changed every 15,000 miles when using Dexron II and 50,000 miles when using Dexron III or equivalent. Otherwise, change the fluid every 100,000 miles, using Dexron II,III or equivalent automatic transmission fluid.