Automatic or Manual, your transmission
transfers power from the engine to
your drives wheels.
The transmission’s primary job is to allow the engine to operate in its narrow range of speeds while providing a wide range of output speeds to the vehicle’s differential and tires.
Without a transmission, vehicles would be limited to one gear ratio, and that ratio would be selected to allow the vehicle to travel at the desired top speed.
The key difference between a manual and an automatic transmission is that the manual transmission, through the use of a clutch, locks and unlocks different sets of gears to the output shaft to achieve the various gear ratios, while in an automatic transmission, the same set of gears produces all of the different gear ratios automatically.
The planetary gear set is the device that makes this possible in an automatic transmission. So the transmission uses gears to make more effective use of the engine’s torque, and to keep the engine operating at an appropriate speed.
When your transmission is running properly, it transfers power from the engine to the drive wheels. When it is clean and well – lubricated, it gives maximum fuel efficiency. However, when it gets dirty or worn down, your fuel efficiency will suffer. Your transmission relies on transmission fluid to keep everything running well.
The constant shifting and movement of the gears inside the transmission cause bits of the gears and clutch material to wear off. These metal bits of dangerous grit get into the transmission fluid. This grit increases friction inside the transmission and causes even more wear, kind of like liquid sandpaper.
The high temperatures inside the transmission cause the transmission fluid to break down over time which makes it a less effective lubricant. The fluid can actually become sludgy. When this happens, it can gradually plug up the maze of passages inside the transmission. The lubricant is blocked and cannot get to all the parts to protect them, making them wear out prematurely.
The transmission will gradually lose efficiency and will stop operating smoothly. Eventually, the transmission will be damaged or fail altogether.
Hot and dusty conditions; towing, hauling, stop and go conditions all increase the load on the transmission and its internal temperature. Therefore, the fluid needs changing more often.
A good rule of thumb is every 30,000 to 50,000 miles or two years, if your manufacturer suggests more frequent intervals or if you are driving under severe service conditions you will need to change it more often.
Refer to the “Fluid Flush” section to learn how to extend your transmission’s life.