Change Manual and Automatic Transmission Fluid

Change Manual and Automatic Transmission Fluid

A step-by-step guide to replacing your car's transmission fluid and filter to ensure longevity and optimal performance.

Transmission fluid is required to lubricate and cool the transmission components. If you want your transmission to last for a long time, you need to change the fluid and filter at regular intervals. Old, worn-out fluid does not work as well, and clogged filters are much less efficient. New fluid is bright red, whereas old fluid is a much darker red, almost black.

Many people wonder how often they should change their transmission fluid. Automatic transmission fluid and filters should be changed every 15,000 to 30,000 miles (or every 2 years) as part of your basic car maintenance. It is important to change both the filter and the fluid at each interval. Do not wait until the transmission begins to slip.

Here is how to change your automatic transmission fluid:

1. Preparation: Buy the correct fluid at an auto supply store. Your owner's manual should indicate the correct type of fluid for your car. Also, get a new filter.
2. Tools: Here is a list of all the tools you will need:
   • Floor jack - to lift the car
   • Jack stands - to hold the car up while you are working
   • Drain pan - large enough to hold at least 5 quarts
   • Newspaper
   • Clean shop rags
3. Block the tires and set the emergency brake.
4. Remove one of the transmission cooling lines running to the radiator. Connect a tube to the end of the line, and place the other end in a drain pan. Start the car and let it idle for a minute or two. Transmission fluid should flow out of the cooling line, through the tube, and into the drain pan. Turn the engine off as soon as the fluid stops flowing.
5. Raise the car with a jack and secure it with jack stands. Do not put any part of your body beneath a vehicle unless it is properly supported.
6. Place the drain pan underneath the bottom of the transmission pan, centered toward the front. Put newspaper underneath the drain pan in case of any spills.
7. Remove all but the rear bolts holding the pan to the bottom of the transmission. Loosen the rear bolts last, only turning them a few times.
8. If the pan has not lowered already, use a flat-head screwdriver to gently separate it from the rest of the transmission. It should tilt so that fluid can flow out of the front end of the pan into the drain pan.
9. When fluid stops coming out, remove the last few bolts at the rear and lower the pan the rest of the way. Pour the remainder of the fluid into the drain pan.
10. Remove the old gasket and thoroughly clean the transmission pan with solvent. Let it dry in a clean place.
11. Pull the old filter out of the transmission and replace it with the new one.
12. Put a new gasket on the cleaned transmission pan, and place the pan back onto the bottom of the transmission. Insert the bolts and hand-tighten them. Then use a wrench to tighten the bolts a little at a time, ensuring they are tightened evenly to avoid bending the transmission pan.
13. Remove the jack stands from the vehicle and add the correct amount of fluid. Your owner's manual will tell you how much to add, which is usually about 7 pints.
14. Check your work: Start the engine and let it idle for a few minutes. Set the parking brake and shift between gears, then check the fluid level with the engine running. If the fluid is low, add a little at a time until the dipstick indicates a sufficient level.

Manual transmissions have far fewer moving parts and are much more robust, but most manufacturers still require lubricant changes every 30,000 miles (or every 2 years). Changing the fluid on a manual transmission is very similar to changing your car's oil and is a bit easier than an automatic transmission. Here is how to replace manual transmission fluid:

1. Drive around the block a time or two in order to warm up the fluid.
2. Lift your car with a good jack and properly support it with jack stands.
3. Place a drain pan beneath the drain plug on the transmission and use a wrench to remove the plug. Watch out—the fluid is hot! Once the fluid stops draining, put the plug back in and tighten it securely.
4. Adding fluid back into the transmission can be a little tricky. Locate the fill plug about halfway up the side of the transmission, remove it, and add fluid through the fill hole. Because space may be limited, you might need to use a small funnel, syringe, or a specially designed pump. Once the fluid is added, put the bolt back on and tighten it securely.
5. Lower the car, start the engine, and drive around the block. Carefully look for leaks around the drain plug and fill plug. If you find no leaks, pat yourself on the back for a job well done.