Over 90% of all Automatic Transmission failures are due to overheating and fluid contamination.
Typical transmission drain-and-refill services replace only 40% of the old contaminated Automatic Transmission Fluid (ATF).
The remaining ATF is trapped inside valve bodies, the torque converter and transmission cooler lines. This means more than half of the ATF is not being replaced and eventually mixes with the new fluid. Not an ideal scenario in any circumstances, especially when you consider that an Automatic transmission replacement can cost more than $2,500 depending on the vehicle you drive.