CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Checking your trans fluid levels

I have been told you should check your trans fluid after the car has been running for at least 30 minutes and while the engine is running. I have also been told you can check it after starting car, drive around the block a couple of times and return home turn off engine and check levels. What is the best way to check your fluid levels for your transmission. I have also been told that it is the only fluid you check with the engine hot all others should be checked (brake/PSF/oil/antfreeze) when the car is cold, like first thing in the morning.

My car:

2001 Kia Sedona
175,000 miles

The car should be driven as you stated and then checked with the car running. Your owners manual will give you all the details. Here is a video.

http://www.carcarekiosk.com/video/2010_Kia_Sedona_LX_3.8L_V6/transmission_fluid/check_fluid_level

The I check all my other fluid first thing in the morning cold.

Unfortunately many vehicles these days there is no tranny dip-stick.

Every automatic transmission I’ve ever been associated with was supposed to be checked for fluid level with the transmission warm and the engine running. The parts within the tranny expand to take up a small amount of additional space, so checking cold will give a slightly different reading.

Now what about the “modern” cars with no dipstick for the transmission? Poor idea IMHO.

Kia gave you the answer in your owner’s manual. Do you not believe what they wrote?

MG McAnick wrote:
Every automatic transmission I’ve ever been associated with was supposed to be checked for fluid level with the transmission warm and the engine running.

On my old Acura MDX, the fluid was checked with the engine off (but hot).

The transmission fluid should be checked with the car running, unless it should be checked with the car not running. It should be checked warm at operating temperature unless it can be checked at any temperature from ice cold to boiling hot.

Many cars are checked running. Almost every Honda has the fluid checked with the engine off. Many cars have a “low” and “full” mark based on warm fluid. Others use a graduated disptick based on fluid temperature with as many at 10 marks indicating full. Others have you measure the fluid temperature and when it’s in a specific range make you check the level using a fill plug on the side of the case.

There is no one answer. But for your car I’d check it at operating temperature with it running.

I bought the van used in 2010…no owners manual…

If I spent a nice chunk of money on a car, I’d make the effort to track down an owner’s manual to make sure I maintained the car properly and kept it running as long as possible (and also didn’t pay for unnecessary service). I’m afraid I’m baffled by people who don’t feel the same way.

I use sites like this for info.

The only manuals I can find go back to 2002 Sedona.

A trip to the dealer to ask would be worth it. On GMs you need to have the fluid hot but not too hot and checked running. On my Acura they have a very specific sequence to follow such as waiting until the radiator fan comes on twice, then shutting the car off and checking within 60 seconds. My Pontiac needs to go into the shop to check it. So nothing generic anymore.

Some sticks would have “cold” and “hot” zones on them. As mentioned, Honda needs to be checked after warm up but with the engine off “for a few minutes” for the ATF to settle. Kind of an OCD ritual IMO. On my previous Mitsubishi, the engine had to be running and the transmission in Neutral, if I put in in Park, I would get fluid all over the stick (By the way, some Hyundai and Kia automatic transmissions are outsourced from Mitsubishi).

In addition to the engine running and the tranny hot, the shifter is supposed to be run through the gears once to get fluid everywhere.

BUT, since manufacturers have over the years differed some on the method, you should ALWAYS read the owner’s manual and follow its instructions when checking the fluid… assuming your tranny still allows you to check your fluid. Trannys themselves are now sometimes CVTs or (in high-end cars) really have a lot more in common with manuals than with automatics. It’s never wise to make assumptions when dealing with trannys.

Why do you check the trans fluid when the engine is hot and running but check all other fluids when the engine is cold and not running?

Engine oil is checked with the engine off because the dipstick was designed to measure how much oil is in the pan and with the engine running much of the oil is circulating in the upper part of the engine.

Engine coolant may be checked hot or cold and with the engine running or not. But since I don’t want to open up a radiator cap that’s holding boiling hot fluid at 16psi pressure, I try to check them cool and off.

Brake, power steering, and washer fluid can be checked running or off, doesn’t matter. But on many cars, power steering fluid is right next to the belts. Don’t want to get your fingers caught.

Transmissions, some checked running some checked off. Depends on the car.

Let car idle 2 min. Shift through all gear selections, check level with engine idling.

@asemaster, check the coolant level in the reservoir when hot. Almost all are translucent with ‘low’ and ‘full’ lines on them. When cold, you can check to see if coolant is in the reservior and the radiator is topped off if the rad cap is on the radiator. I’ve seen some cars with rad caps on the thermostat housing and on an expansion tank, same rule applies, open only when cold. With those with rad caps on the reservoir, just read the coolant level on the reservoir, hot or cold.

http://www.agcoauto.com/content/news/p2_articleid/89

Quoting from that informative link

“General guidelines for transmissions with a dipstick
1.The transmission needs to be at normal operating temperature. We should drive the vehicle at least ten minutes before attempting to check the automatic transmission fluid level.
2.For an accurate fluid level reading, the vehicle must be level.
3.To distribute the fluid, start the vehicle and slowly move the shifter to every position, including the lower gears. We check most vehicles in Park position, with the engine running and parking brake set.
4.On vehicles with a dipstick, we must read both sides of the stick. The LOWEST reading is the correct fluid level.
5.If a void or gap shows in the transmission fluid level, the LOWEST reading is the correct reading.
6.Check the automatic transmission fluid level at least twice, wiping the dipstick clean between readings.”