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Transmission Cooler Guide & How To Install an Inline Transmission Cooler

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An auxiliary cooler can greatly extend the life of your transmission fluid and your transmission

No, not the ones with the beverages in them - the ones that help save you the cost of a transmission rebuild. Truth is, all that stop-and-go traffic generates heat inside your automatic transmission. Heat kills transmissions. More specifically, heat kills the transmission fluid.

Cooler Transmissions Equal Longer Fluid Life

Most automatic transmissions will run effectively at a range of 170-175 degrees Fahrenheit. If the temps are maintained at that level, your fluid could last up to 100,000 miles. Unfortunately, if that temp increases by just 10 degrees, your fluid life could decrease by up to 50%. Most stock vehicles have some form or another of a cooler for the transmission fluid. There are several ways you can help this cooling process.

A Deep Finned Transmission Pan Can Dissipate Heat
A finned aluminum pan dissipates heat to provide better transmission fluid cooling

First, change the transmission filter. Even a filter that is slightly clogged will reduce the flow of fluid, resulting in higher friction, and friction builds heat. Next, consider changing the smooth transmission pan to a finned automatic transmission pan. By building fins into the pan, you increase the surface area that cool air passes by and in turn increase the cooling capacity of the pan. Derale offers a series of transmission cooling pans that incorporate built-in cooling tubes which flow cool air through the ATF. Combined with their 2-quart increased capacity and heat-dissipating coating, these pans can reduce fluid temperatures 20-50 degrees. Every little bit helps, right?

If those aren’t doing the trick to help, an auxiliary transmission oil cooler may be the next best option. Speedway Motors offers several options for you to choose from, from a single pass inline unit to four pass and even multi-pass kits like one from Derale that comes complete with cooler, hose, brackets and mounting hardware.

Auxiliary Transmission Oil Coolers Provide Maximum Transmission Cooling
An auxiliary cooler such as this one-pass inline cooler reduces heat returning to the radiator, where the factory cooler is located

If you intend to mount an inline cooler for your transmission, there are a couple things that you need to keep in mind. First, make sure you use a barbed fitting to tie into your existing lines. Transmission lines are pressure lines, and without that barbed fitting you can blow a line off and drain your transmission (not good!). Next, install it on the return side, after the factory cooler. This reduces the heat being introduced to the radiator, which is usually where the factory cooler is located. Lastly, location is also important. Please don’t bolt the cooler to your exhaust. We’ve seen it happen. Try and locate the cooler where it will achieve maximum airflow.

A simple installation of an auxiliary transmission cooler can provide basic cooling benefits
Routing your transmission cooling through the vehicle's cooling system is the most effective means of cooling your transmission

Auxiliary coolers are usually rated in Gross Vehicle Weight, and this figure can be found on the Vehicle ID plate that is mounted to the door-jamb of most American vehicles. In comparison to the cost of a transmission rebuild, these options are by far the most beneficial.

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