An automatic transmission, also called auto, self-shifting transmission or AT, is a type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually. Like other transmission systems on vehicles, it allows an internal combustion engine, best suited to run at a relatively high rotational speed, to provide a range of speed and torque outputs necessary for travel.
In Automatic transmissions the average service interval is almost 40,000KM. It is also advisable to have the shift points re-calibrated after the replenishment of fluid. Some automatic transmissions having CVT and WS fluids can run lifetime.
However the ATF can get burned if excessivley used, and may require an earlier change if the use is heavy duty, highway in extreme temperatures specially for Honda Civics lacking the ATF cooler / warmer in some models.
The obvious advantage of an automatic transmission to the driver is the lack of a clutch pedal and manual shift pattern in normal driving.
A continuously variable transmission (CVT)is also known as a shiftless transmission. It is an automatic transmission that can change seamlessly through a continuous range of effective gear ratios. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios. The flexibility of a CVT with suitable control may allow the input shaft to maintain a constant angular velocity even as the output speed varies.
Use right ATF fluid for your transmission
It is also pertinent to note that all automatic transmission cars use ATF fluid further segregated into CVT, CVTF, Nissanmatic, Mitsubishi J1/J2/J4 , HMMF, Multimatic etc. ATF III also have some special fluids designed by manufactureres such as Toyota TIV, Mitsubishi Diaqueen SPIII, Honda DW1 etc.