Relatively low mileage transmissions that are regularly used in city or stop and go conditions are subject to much higher wear than transmissions of the same mileage which are used under normal or primarily highway conditions. It is important to note it's not necessarily the mileage on a transmission that determines probable wear. Instead, it's the number of times the transmission has been run through its startup and shift cycles that determines wear. Many other seemingly normal driving conditions can also affect transmission life. Conditions like extreme climates either--cold or hot, mountainous, driving, motoring problems associated with snow or ice (and a host of others) can all take their toll. Under 'normal' driving conditions, vehicle manufacturers recommend servicing the transmission as seldom as every 100,000 miles.However very few motorist fit into the ideal or 'normal' driving condition category.
If you operate your vehicle under more extreme conditions, more frequent transmission servicing will be necessary to maximize transmission life. Servicing your transmission yearly seems to be an industry average. Under the most extreme conditions, even more often may be advisable and you may want to install an external transmission cooler for additional protection.
We are all aware that late model cars use a computer to control the engine. Many cars use the same computer or another computer which shares the same information to control the fuel injectors, ignition & transmission. Automotive engineers did this in order to achieve more efficiency and gain better mileage. This means that your engine and transmission are connected together in more ways than just simply being bolted together.
Since the engine and transmission are controlled and work together, they are referred to as a “power train.” Consider that shudder you felt cruising down the highway. The computer is using sensors on the engine and transmission to detect such things as throttle position, vehicle speed, trans input speed, stop light switch position. etc. As you drive the car, you are constantly changing the demands on the power train (acceleration, cruising, passing, coasting, & idling). The computer recognizes this by monitoring various sensors.
Without special equipment and engineering, no one can tell if a shudder is caused by something slipping inside the trans, the torque converter, a weak spark, a dirty fuel injector or a loose electrical connection. The certified transmission technicians at USA Transmissions are qualified specialists who you can trust to determine what service--if any—that your transmission may need.