Car inspection: How to check automatic transmission system and add transmission fluid?

An automatic transmission is one of hydraulic systems in a car. In order to maintain automatic transmission system, automatic transmission fluid must be checked regularly to ensure that there is enough high quality transmission fluid in it to keep vehicle running well. The following methods will help you learn how to add transmission fluid to an automatic transmission.

Steps

Car inspection: How to check automatic transmission system and add transmission fluid?

1. Park vehicle on a level surface and leave engine running. It may be necessary to set rotator to temporarily shift gears until the vehicle is parked.

2. Open hood. Inside lid there is a lever that supports lid, usually to left of cockpit. If you can't find it, check manual.

3. Locate transmission flow tube. Many new cars will have logo. If it's not a new car, you can find its location in manual.

On rear-wheel drive vehicles, dipstick is usually located at rear of engine, above fuel tank.

On front wheel drive vehicles, dipstick is usually located at front of engine where it connects to transmission. On most vehicles, it should be to right of fuel tank.

4. Remove rotating fluid dipstick. Wipe dipstick with a clean rag or paper towel, then reinsert and remove to check transmission fluid level. The fluid level between two marks should be marked "full" and "refill" or "hot" and "cold".

Normally, automatic transmission fluid does not need to be added. If fluid level is significantly lower than "Full" or "Cold", there is a good chance that there is a leak in one of systems, which will require vehicle to be taken to a repair shop.

5. Check condition of automatic transmission fluid. Good quality automatic transmission fluid is usually red in color (although sometimes pink or light brown), without foam or odor. If any of following situations occur, vehicle must be sent to a service station for overhaul.

If automatic transmission fluid is brown or smells like toasted toast, it is no longer used to remove heat from CVT. You can further verify that transmission fluid is invalid by applying a small amount of transmission fluid to a clean paper towel and waiting 30 seconds to see if it spreads. If it does not spread, then transmission fluid must be changed immediately, otherwise transmission will suffer more serious damage.

If ATF is milky brown, ATF is contaminated with leaks as coolant in radiator passes through ATF cooler. Take car to a repair shop immediately.

If there is foam or air bubbles in ATF, there must be too much fluid in cylinder, wrong ATF was used, or engine ATF vent valve is clogged.

6. Add some automatic transmission fluid if necessary, but only a small amount at a time, check regularly until level is correct.

During first run, you may need to add 3 to 4 liters of transmission fluid if you are starting over because oil pan is completely damaged. Also, check dipstick regularly to make sure fluid pan is not overfilled.

7. Start car and, if possible, run transmission fluid through each gear. This step is to continuously circulate newly added transmission fluid, coating and lubricating each gear. Park vehicle with engine running and, if possible, keep wheels in air. Run transmission fluid through drive, overdrive, then reverse gear and wait a few minutes to make sure each gear is coated with oil. When finished, let engine run for a few minutes before parking car.

8. Check dipstick level again to determine how much transmission fluid needs to be added. Check dipstick, as gear oil may be leaking between oil pan and gears, so a different fluid will be needed.

9. Add correct amount of transmission fluid to maintain normal fluid levels. The amount to add depends on whether you are adding transmission fluid or replacing entire oil pan with new transmission fluid, at which point additional automatic transmission fluid will need to be added.

A liter of transmission fluid is enough, if not less, for a simple top up.

If you are starting over because oil pan is completely damaged, you may need to add 4 to 12 liters of transmission fluid, depending on the make and model.

10. Ready. Now that automatic transmission fluid is good, car should be humming.

Tips

When you need to change automatic transmission fluid, read owner's manual first. If you frequently drive on mountain roads or tow a heavy trailer, you may need to change your transmission fluid more frequently. Whenever transmission fluid is changed, filter used by transmission fluid must also be changed.

Always use an automatic transmission fluid recommended by vehicle manufacturer for your make and model.

Warning

If you see red oily fluid in driveway, it's an automatic transmission fluid leak. If you suspect a leak but don't know where, place a stack of thick white paper under car to better locate leak.

You need to prepare

Automatic transmission fluid

Funnel for automatic transmission fluid lines.

Products or paper towels

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