Most of us drive a car with an automatic transmission. We like the fact that an automatic transmission lets us stop and start without requiring the use of a clutch and gear shift lever to shift gears, as is the case with a manual shifting transmission.
Unfortunately, the poor automatic transmission, which is so kind to us (taking care of all that annoying shifting), is frequently one of the most neglected items on a car. That's too bad, because neglecting the automatic transmission can eventually result in an expensive repair bill, or even require a new transmission.
What can you do to show your automatic transmission that you care? Check its fluid level at least once every six months, preferably more often. Maintaining the transmission fluid level at its proper height and changing transmission fluid and filter at the intervals recommended by your car's maker will likely let your automatic transmission last for as long as you drive the car.
Check your owner's manual or shop manual for the specifics on checking the fluid level in your car. The transmission fluid should be at operating temperature -- so drive the car around for 10 or 15 minutes, or check it when you come back home from shopping or work.
In any case, the transmission is checked with the engine idling, and the parking brake on. Some makers, though, may want you to check the fluid level with the gearshift lever in park, others may want you to check it with the gearshift lever in neutral.
Many transmission dipsticks have the instructions printed on them for checking, such as "check when hot -- idling-in-neutral."
The car should also be parked on a level area when checking the fluid level (this holds true when checking any fluid level in a car).
Before removing the dipstick, wipe off any dirt that may be present on the protective cap on the dipstick (that's the cap that fits over the filter tube). Also wipe any dirt off the filler tube itself that's around the area of the cap.
You can wipe dirt off with a paper towel or old cloth. But heavy dirt comes away easier and faster if you spray a little carburetor cleaner (available in spray cans at just about any place that sells auto supplies) on the towel or cloth, and then wipe.
With the engine idling and the transmission in park or neutral (as recommended by the maker), remove the dipstick and wipe off the transmission fluid from it with a dry cloth or paper towel, Reinsert the dipstick until it seats completely (until the protective cap on the dipstick rests against the fill tube). Now withdraw the dipstick again and note the fluid level on the dipstick.
The fluid level should be between the "full" and "add" marks on the dipstick. If the fluid level is at or below the "add" mark, add transmission fluid until the fluid level is at the "full" mark on the dipstick.
Use the proper fluid when adding fluid. Some transmissions require transmission fluid with Dexron, others require fluid without Dexron. The two types of transmission fluid should not be mixed. Your owner's manual or shop manual for your particular car will tell you what type of transmission fluid you should use.
To add fluid, use a funnel with a thin neck which will fit in the transmission's fill tube (that's the tube that the dipstick fits in), and pour the transmission fluid in slowly, a little bit at a time. You don't want to overfill the transmission. Generally it takes one pint of fluid to raise the fluid level from the "add" mark on the dipstick to the "full" mark.
Do not overfill the transmission. Overfilling can cause the transmission fluid to foam and result in fluid loss through the transmission vent. Slippage and transmission failure can eventually result.
Check the transmission fluid level regularly, and have the transmission fluid and filter changed, or change it yourself, at the intervals recommended in your owner's or shop manual.
Treat your transmission right, and it'll treat you right.