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How to check transmission oil in a car?

Just like your engine needs oil to lubricate the different components and protect them against wear and corrosion, your transmission is as well lubricated by a special fluid called transmission fluid.

Maintaining the proper transmission fluid level is important to keep your transmission shifting properly and your car running smoothly.

How do I check my transmission fluid?

  • Step 1: Check your owner’s manual. Do you have a manual or an automatic transmission? Manual transmissions don’t usually have a dipstick. They are factory filled. No top-up is needed. The fluid only has to be changed in the event of repairs.
  • Step 2: Locate the transmission dipstick if you have an automatic transmission. The transmission fluid dipstick is usually red (yellow or white for the engine oil dipstick). The owner’s manual will help you find the dipstick. If you're lucky, it will be indicated where you can find it.

On rear-wheel drive vehicles, the dipstick is usually on the passenger side of the engine compartment, near the back of the engine.

On front-wheel drive vehicles, the dipstick is usually on the driver’s side, on one side of the transmission. If you don’t find it, your owner’s manual should show you where to look for it.

Many cars don’t have a transmission dipstick. The oil level may have to be checked using an electronic device or by removing a screw in the transmission housing. Checking fluid levels in a sealed transmission is a much more complicated process. The average car owner does not have the skills required to check the transmission fluid level. If your car doesn’t have a dipstick have your local transmission shop or dealership check the level. A good time to do this is while you’re having the engine oil changed. If your car has a transmission dipstick, you should check the transmission fluid level regularly.

  • Step 3: How to check transmission oil?

Remove the stick, wipe it with a clean cloth, reinsert it, leave it in for 5 seconds, then pull back out and check. Add fluid if necessary. Always use the fluid recommended by the manufacturer.

Add only a little at a time, checking the level with the dipstick each time. It's easy to add transmission fluid, but fairly difficult to remove it if you add too much.

If the transmission requires more than a quart or is using fluid regularly, take your car in to have it checked for leaks.

How to properly check transmission fluid?

You can also check the color and smell. Color is very important for transmission oil. It should not change from its normal light brown, semi-transparent appearance. Automatic transmission fluid (ATF) is a cherry red. If it is dark red or brown, you should have your fluid changed.

If it smells burned or has particles in it, you should also have your transmission serviced. What is a transmission service? It consists of changing the transmission fluid filter before adding the transmission fluid.

How to check automatic transmission fluid?

What is automatic transmission fluid?

Automatic transmission fluid (ATF) is the fluid used in vehicles with automatic transmissions. It is usually red or green.

Why check the automatic transmission fluid level?

Automatic transmission fluid is the lifeblood of the transmission. The fluid produces the hydraulic pressure needed to operate the transmission. It also cools and lubricates the transmission. When the fluid level is low, the pump may draw air into the system. Air in the hydraulic system interrupts the proper flow of automatic transmission fluid. Damage can occur very quickly when transmission fluid is low.

How to check automatic transmission fluid level?

For transmissions with a dipstick, the procedure is the same as described above.
Many Fords, Toyotas, GMs and other vehicles no longer have an automatic transmission dipstick for checking the fluid level. Automakers are eliminating automatic transmission dipsticks. Newer transmissions are far more complex than older models and the transmission fluid levels are far more critical. Special procedures are required to check the automatic transmission fluid level in these models.

If you want to go further, learn how to change automatic transmission fluid:

  1. Drain the transmission fluid: First, disconnect the cooling line running from the transmission to the radiator. Connect a piece of rubber tubing to the pipe and place the free end of the tube in an empty container. Start the engine and let it idle. Transmission fluid should flow out of the cooling line and into the container. As soon as the fluid stops flowing, turn off the engine. You can then reconnect the cooling line to the radiator.
  2. Remove the bolts holding the drain oil pan to the bottom of the transmission.
  3. Clean the drain pan with transmission fluid.
  4. Replace the filter.
  5. Replace the gasket.
  6. Replace the pan: Once the filter and gasket are in place, put the pan back on the transmission. Hand-tighten the bolts for the first few turns so that you don't strip the threads. Then use a torque wrench to finish tightening the bolts. Do not overtighten the bolts or you will damage the threads in the transmission and dent the pan.
  7. Fill with automatic transmission fluid: Dexron III ATF is the most common, but refer to the owner's manual to choose the appropriate automatic transmission fluid. Check the amount as well.