Toyota Pick-ups, Land Cruiser, and 4 Runner 1997-00




One of the most common, if not THE most common, problems associated with trailer towing is engine overheating. The vehicle's cooling system should be regularly serviced so it will operate at peal efficiency.

Aftermarket engine oil coolers are helpful for prolonging engine oil life and reducing overall engine temperatures. Both of these factors increase engine life. While not absolutely necessary in towing Class I and some Class II trailers, they are recommended for heavier Class II and all Class III towing. Engine oil cooler systems consists of an adapter, screwed on in place of the oil filter, a remote filter mounting and a multi-tube, finned heat exchanger, which is mounted in front of the radiator or air conditioning condenser. It would be wise to consult with your Toyota dealer before making any modifications to your truck's cooling or engine oil systems.


An automatic transmission is usually recommended for trailer towing. Modern automatics have proven reliable and, of course, easy to operate, in trailer towing. The increased load of a trailer, however, causes an increase in the temperature of the automatic transmission fluid. Heat is the worst enemy of an automatic transmission. As the temperature of the fluid increases, the life of the fluid decreases.

Although automatic transmissions normally have remote coolers, many trailer towing vehicles will have an additional automatic transmission cooler. The cooler, which consists of a multi-tube, finned heat exchanger, is usually installed in front of the radiator or air conditioning condenser, and hooked in-line with the transmission cooler tank inlet line. Follow the cooler manufacturer's installation instructions and consult with your Toyota dealer before making any modifications to your truck's transmission fluid systems.

Select a cooler of at least adequate capacity, based upon the combined gross weights of the vehicle and trailer. Cooler manufacturers recommend that you use an aftermarket cooler in addition to, and not instead of, the factory-installed automatic transmission cooler. If you do want to use it in place of the factory-installed cooler, get a cooler at least two sizes larger than normally necessary.

A transmission cooler can, sometimes, cause slow or harsh shifting in the transmission during cold weather, until the fluid has a chance to come up to normal operating temperature. Some coolers can be purchased with or retrofitted with a temperature bypass valve that will allow fluid flow through the cooler only when the fluid has reached above a certain operating temperature.