Hobbies Cars & Motorcycles Does Your Truck Need a Transmission Cooler Upgrade? Share PINTEREST Email Print shaun/Getty Images Cars & Motorcycles Cars How Tos Buying & Selling Basics Reviews Tools & Products Classic Cars Exotic Cars Corvettes Mustangs Tires & Wheels Motorcycles Used Cars SUVs Trucks ATVs & Off Road Public Transportation By Matthew Wright Matthew Wright has been a freelance writer and editor for over 10 years and an automotive repair professional for three decades specializing in European vintage vehicles. our editorial process Matthew Wright Updated June 07, 2018 Pickup truck owners seeking enhanced towing capacity might wonder if they need to upgrade to a transmission cooler. Back in the old days—way back in the old days—the radiator was the only part of a truck's drivetrain that owners needed to keep cool. And that was simple. Fill it up with a mixture of antifreeze and water, make sure the radiator cap was on nice and tight, and then check the fan belt for tightness and wear. Today's trucks, however, are far more complicated and advanced than the carbureted haulers of old. One of the many advances made in truck manufacturing has been the option to install a transmission cooler. No, this isn't an ice pack that you stick underneath the truck to keep things cool. But it might help improve your towing performance. Transmission Run Down For those of you unfamiliar with the anatomy of a heavy-duty automatic transmission, here's a quick rundown. Your transmission is full of a fluid called, well, transmission fluid. This fluid is part of a complex hydraulic system that transfers the power of your engine to the wheels. The fluid in your transmission is always moving. When you are pulling a trailer or hauling a very heavy load, the transmission fluid finds itself under a lot more pressure than it experiences during normal unloaded cruising. This pressure and velocity produce heat. Under normal circumstances, this heat is dissipated through the transmission case itself. It's a great conductor of heat and can pretty much keep the system cool without any outside help. What a Transmission Cooler Does Of course, you didn't get a truck so that you could always operate it under normal conditions, right? As you tow heavier loads for longer periods of time, the metal body of the transmission can't dissipate enough heat to keep the fluid cool. The fluid can become so hot that it loses its hydraulic qualities and starts to make the transmission slip. To fix this problem, automotive manufacturers came up with the transmission cooler, which takes the heated tranny fluid and runs it through a miniature radiator to cool it down. It's amazing how much cooling can happen with even a small one of these devices. When to Consider a Transmission Cooler Most trucks these days come with optional towing packages that almost always include a transmission cooler. Some trucks that didn't come with the towing package may already have the plumbing to install one, and just need the addition of the radiator section. But just because you're doing a little towing doesn't necessarily mean you need a transmission cooler. If you're pulling something big and heavy like a camper, you may want to make the upgrade. On the other hand, something small like your bass boat will pull along just fine without heating the system up any more than regular driving would. If you plan to tow big, or if you plan to tow a trailer on top of loading the truck's bed to the top, you may want to consider going with a cooler. If you've already had problems with your truck's transmission overheating, your decision is a no-brainer. Upgrading an Existing Cooler If you're lucky enough to have a truck that came equipped with some type of transmission cooler, it's often very easy to upgrade to a medium-duty or heavy-duty unit. The same criteria apply here as above. The type of towing you plan to do, what type of terrain you live near, and the weather in your towing season are all factors that can affect your need for greater transmission cooling capacity.