Towing a trailer puts extra stress on your vehicle’s automatic transmission. Heat and load can cause premature wear if you don’t adapt your driving habits. These six practical tips will help you keep your transmission healthy and your towing experience safe.
Use Tow/Haul Mode if You Have It
Most modern trucks and SUVs come with a tow/haul mode button. This setting changes shift points and shift firmness to better handle the extra weight. It keeps the transmission in lower gears longer, which helps with engine braking on descents and reduces hunting between gears on hills.
- Engage tow/haul mode before you start moving with a trailer.
- Leave it on for the entire trip, even on flat highways.
- If your vehicle lacks this mode, use a lower gear range instead (see below).
Manually Select Lower Gears on Hills
Even without a dedicated tow mode, you can protect your transmission by manually shifting. On steep grades, select a lower gear (like 3 or 2) to prevent the transmission from constantly shifting up and down. This reduces heat and wear on the clutches and bands.
On long downhill stretches, use engine braking to slow down instead of riding the brakes. This keeps the transmission in a lower gear and prevents brake fade, which is a safety hazard.
Avoid Overdrive When Towing
Overdrive gears are designed for fuel economy at highway speeds with no load. When towing, the torque converter may constantly lock and unlock, generating excessive heat. Many owners’ manuals recommend turning off overdrive (usually via a button on the shifter or column) when towing.
If you don’t have an overdrive lockout, use the next lower gear (like D4 instead of D5 or D6). This keeps the engine RPM higher and reduces strain on the drivetrain.
Check Transmission Fluid Regularly
Transmission fluid is the lifeblood of your automatic gearbox, especially when towing. Hot fluid breaks down faster, so check the level and condition before and during long trips.
- Park on level ground and run the engine until warm.
- Pull the dipstick and wipe it clean, then reinsert and pull again.
- Fluid should be at the “hot” mark and bright red or pink, not brown or burnt smelling.
- If it looks dirty or smells burnt, have it changed before towing again.
Let the Engine and Transmission Cool Down
After a long pull, especially in hot weather, your transmission can reach temperatures above 220°F. Before shutting off the engine, idle for a few minutes to let the radiator fan circulate air through the cooler. This is particularly important if you have been climbing grades or driving in stop-and-go traffic.
If your vehicle is equipped with a transmission temperature gauge, keep an eye on it. If it enters the red zone, pull over safely and let the engine idle until it cools.
Know Your Vehicle’s Cooling Limits
Transmission cooling is often handled by a separate cooler integrated into the radiator or an auxiliary cooler. If you tow frequently or in extreme conditions, consider an aftermarket transmission cooler. Many vehicles also have a “max trailer weight” rating that assumes proper cooling equipment.
Before you tow heavy loads, check your owner’s manual for specific recommendations about transmission cooling. Some vehicles require a heavy-duty cooling package to safely tow near the maximum rating.
Frequently Asked Questions
Can towing with overdrive damage my transmission?
Yes, towing in overdrive can cause excessive shifting and heat buildup, which may damage the transmission over time. It's best to lock out overdrive or use a lower gear when towing to reduce strain.
How often should I check transmission fluid when towing?
Check the fluid level before you start your trip and again after every fuel stop or every few hours of driving. Also, inspect the color and smell for signs of overheating.
What should I do if my transmission overheats while towing?
If the temperature gauge rises into the red, pull over safely as soon as possible. Shift into neutral and let the engine idle for 10 to 15 minutes to allow the fluid to cool. Do not shut off the engine immediately.
