As it turns out, transmission temperature can make or break a transmission. Almost all transmissions fail from a breakdown of the transmission fluid. This is caused by overheating the transmission fluid. Not only is the temperature critical but also how long the transmission is exposed to the particular temperature. High heat will cause damage to seals, burnout clutches, clutches slip, seals harden, varnish forms and the fluid burns.
What is the optimum temperature for the longest life of the transmission?
Keeping the transmission temperature between 175 and 200 degrees will allow the fluid to last the longest. This is the normal operating temperature for a transmission. Remember the fluid is the life line or blood of the transmission. Damage to the transmission fluid begins at 225 degrees. Towing, pulling heavy loads, Snow Plowing and stop and go traffic will raise the transmission temperature.
How long will the transmission fluid last?
As we said before, this is directly affected by the the temperature and how long the trans fluid is exposed to that temperature. Under normal operating temperatures the fluid is good to go for about 100,000 miles. At 325 degrees, it might last about 500 miles if your lucky. Use the chart provided to gain a better understanding of Approximate Mileage to Transmission Failure at Average Temperatures.