TRANSMISSION FLUID

Automatic transmission fluid (ATF) should be checked every 3 months or 3,000 miles. Check the level as well as the condition of the fluid.
 

Checking the Transmission Fluid Level
In most cases, the engine should be warm and is usually left running while you check the transmission fluid level. On some vehicles the level is checked with the engine off (but this is not usually the case), so check your owner's manual for information specific to your vehicle.
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It's also a good idea to briefly shift through each gear (from park all the way down to first gear or low) and then return to park before checking the level. This can help distribute the fluid for a more accurate reading. Here's how to check the level:

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1. Engine should be at operating temperature and idling (or off if specified for your vehicle) and the transmission should be in park (or in some cases, neutral).

1. Open the hood and find the transmission fluid dipstick.

2. Pull out the dipstick and wipe it off with a clean napkin.

3. Reinsert the dipstick fully, and pull it back out.

4. Read the fluid level.

A transmission dipstick (highlighted in the upper right corner of the photo).

If the level is anywhere between the ADD and FULL mark, you don't need to add any fluid. Reinsert the dipstick and close the hood.
 

What if I Can't Find the Dipstick?
Note that some modern vehicles do not have a dipstick for the transmission fluid. In this case, the fluid level is usually checked via a plug in the side of the transmission. This requires the vehicle to be properly jacked up or lifted on a hoist, and is often better left to a professional. If you're unsure if your vehicle has a transmission fluid dipstick, check your owner's manual. 
 

How to Read a Dipstick
Dipstick styles can vary quite a bit, but most have holes, lines, notches or a crosshatched area to mark full and low levels. Some are also reversible, with cold fluid level marks on one side and hot fluid level marks on the other. Regardless of style, it's best to check both sides of the dipstick. If the level varies between each side, the correct reading will always be the lowest of the two.
 

• IIf the transmission fluid level is too low, the transmission may not engage or may begin to slip (which causes the engine to rev too high). It can also overheat or get insufficient lubrication. This can result in damage to the transmission.

• If the transmission fluid level is too high, the vehicle may shift erratically or the fluid may start mixing with air and begin to foam (aerate). Aerated transmission fluid does not lubricate, cool, or pump through the transmission as it should, which can result in transmission damage due to insufficient lubrication or overheating.

If your vehicle will not move forward in drive or will not move backward in reverse, the transmission fluid level is the first thing you should check.
 

Transmission Fluid Condition
 

• Automatic transmission fluid should be transparent red in color.

• Transmission fluid that is dirty (brown or black) or that smells burnt should be changed.

• Transmission fluid that appears milky is the result of coolant leaking into the transmission fluid. Have the vehicle serviced as soon as possible.
• Small metal pieces or shavings in the fluid are indicative of internal transmission damage.

Adding Transmission Fluid
If the fluid level is low, be sure to add. Keep in mind that when it comes to the low or add mark, there's a key difference between a transmission dipstick and an engine oil dipstick. The low mark on a transmission dipstick indicates the fluid level is a pint (1/2 quart) low. Remember, the low mark on an engine oil dipstick means the engine oil is one quart low – twice as much as on a transmission dipstick. To add transmission fluid:
 

1. Remove the transmission dipstick (if you haven't already).

2. Insert a funnel with a very small end into the transmission fill tube where the dipstick was.

3. Add up to a pint (one half quart) of transmission fluid.

4. Recheck the fluid level.

5. Repeat if necessary.

Transmission fill tubes can be very small in diameter, hence the need for a small funnel. Also, keep in mind it's easier to add fluid then it is to take it out when it's too full, so add transmission fluid in small amounts and check the level after each addition. Once finished, reinsert the dipstick and close the hood.
 

• Add only the correct transmission fluid (Dexron III, Mercon V, etc.) specified by the manufacturer.

• The type of fluid you should use can be found in the owner's manual, or it may be printed on the dipstick (although this isn't always the case).

Will Any Transmission Fluid Work in My Vehicle?
Using the right fluid is important for proper transmission function and longevity. If for whatever reason you can't figure out what type of fluid your transmission needs, or if you are unsure as to which fluid you should buy among the many choices available on store shelves, ask a parts house or your service center. Do not guess!
 

What About Manual Transmissions?
Manual transmissions often use gear oil instead of ATF, and will not have a dipstick. Because of this, the fluid level in a manual transmission is usually checked in the same manner as with an automatic transmission without a dipstick – via a plug in the side of the transmission. 
 

• Just as with an automatic transmission, a low gear oil level in a manual transmission can potentially lead to damage, wear, and mechanical failure.

Again, because the vehicle will likely have to be lifted for this, have your service center check the fluid level in your manual transmission for you.
 

Get Your Vehicle Serviced if You Notice:
 

• The transmission fluid is dark, dirty, or smells burnt

• The transmission fluid has metal flakes or shavings in it

• The transmission fluid appears milky

• Poor shifting, erratic shifting, or slippage

• Transmission fluid leaks