Dial Herco

“Many people don’t fully understand how heat fries a transmission,” Mayer says. “The transmission will heat up fast while you’re towing because the automatic transmission fluid is moving very quickly through it. Heat breaks down ATh and that leads to premature transmission failure.”
Under normal operating conditions, the temperature of the ATP is about 170° E Stop-and-go traffic can raise the temperature to 250°
F—and that’s without a towing load. In towing conditions, it’s not unusual to get up to 270° E.
“If the temperature gets up to 300° l” Mayer tells me, ‘you better stop at the next gas station, because you’re not going to go much farther than that.You’ve lost it all.”
The easiest and cheapest way to solve this problem is to install an auxiliary transmission oil cooler, which helps ensure that the temperature of the AlT stays in the best operating range. For some reason, many tow vehicle owners resist this option, even though the cost is miniscule ($60 to $120) compared to a rebuilt transmission (as much as $2,000). Another inexpensive transmission-saver is a temperature gauge so you can see when the transmission is headed for trouble.
“I definitely recommend an auxiliary transmission oil cooler,” says Mayer. “Remember, the cooler the transmission oil runs, the better. You’re definitely going to hit yourself in the wallet if you don’t have it.
“I also strongly recommend a drain plug on the automatic transmission—if you can find one.We’ve learned this from vehicles that get heavy usage.When the transmission oil is drained between filter changes, the transmission is a lot less prone to breakdown and failure.”