Auto Transmission Tips & Advice
Should I fit an auto transmission oil cooler?
Because overheating is the main cause of automatic transmission failure, some people choose to install an auxiliary oil cooler for automatic transmission fluid.
Most automatic cars come standard with a separate heat exchanger for the transmission oil just below the radiator. Given the high temperatures you can find in a radiator, often just under the boiling point of water, a short cycle through this heat exchanger doesn’t reduce the temperature of the automatic transmission fluid all that much – only by about 10-20%. Still, with few exceptions, this does the job when you’re only doing everyday driving.
However, if you plan to tow a trailer, boat or caravan, it may be worthwhile having an auxiliary transmission fluid cooler installed.
This is because an automatic transmission takes extra stress when towing, and this raises the temperature in the transmission. Even at just a few degrees hotter than the temperature it was designed for, transmission fluid can become less viscous – not doing its job of lubrication as well as it should and reducing the lifespan of the auto trans.
Similar conditions can develop when you drive in mountains, in heavy traffic or at high speed on hot days.
An auxiliary cooler can keep transmission fluid at optimum operating temperature for longer. Typically, these coolers reduce the temperature by between a third and half from the time the fluid enters the cooler till the time it flows back into the transmission.