When most of us think of summer, we think of vacation, travel, and fun. But for your car’s automatic transmission, summer heat is no laughing matter. Overheating not only shortens the life of your transmission fluid, but also is a major cause of transmission failure. A roadside breakdown and an expensive transmission rebuild or replacement can put a serious dent in your summer fun and your vacation budget. So let’s explore the reasons heat is so hard on automatic transmissions and look at some ways to keep your car’s transmission working better and longer, despite the summer heat.

As the outdoor temperature climbs, your engine relies upon the radiator and coolant to avoid overheating. But what about your automatic transmission? Most automatic transmissions are designed to maintain peak performance at temperatures up to 200ºF. For every 20º above that mark, your transmission’s life expectancy decreases by a factor of two. In other words, at an operating temperature of 220ºF, you’ve cut the life expectancy of your transmission in half. At 240ºF, it’s cut to a quarter, and at 260ºF it’s cut to an eighth.

Also, transmission fluid will begin to degrade as the internal temperature of the transmission climbs. This means less efficient lubrication on moving parts, leading to increased friction, and even more damaging heat. All automatic transmissions are subject to overheating, though high-torque engines and heavy-towing vehicles are particularly vulnerable, as their temps can spike when working hard in summer heat.

So, what can you do to keep your transmission running better and longer when the mercury climbs?

• Check your transmission fluid levels—low fluid levels or fluid levels that drop quickly are warning signs of a transmission fluid leak.
• Change your fluids regularly. Transmission fluid that is degraded or contaminated through normal wear cannot provide adequate lubrication. If you drive a high-torque or “workhorse” vehicle that does heavy towing, check the fluids monthly.
• Use a high-quality synthetic transmission fluid. These are less subject to degradation at higher temps.
• Avoid stop-and-go traffic. City driving is harder on transmissions than highway driving. Your car is shifting more often and not getting the benefit of air-cooling.
• Check your car’s radiator and coolant levels. The radiator controls not only your engine heat but helps your transmission stay cool as well.
• If you want some extra protection, you can add an after-market transmission cooler. If you work on your own vehicle, you an install one yourself, or if not, see a professional mechanic or service center. Prices vary (most between $40 and $130) but are far less costly than a transmission rebuild.
• Another after-market solution is to add a deeper transmission fluid pan to your vehicle. This will provide a larger reservoir from which your transmission to draw.

Hopefully with these tips in mind, you’ll have a summer of safe and trouble-free travel!

About Main Line Transmission: Since 1987, Main Line Transmissions has given drivers in the Wayne, Devon, Berwyn, Paoli, Malvern, Exton West Chester and surrounding areas the best transmission service available. Working only on transmissions of every make or model, our technicians are experts through certification, continual training and years of experience.