There are two main things about tranny fluid:
Transmission fluid is checked when it's hot (up to running temperature). As the fluid gets up to temperature it expands. If the fluid is cold, it won't give the proper level reading, thus overfilling will ensue.
One of the main fluid compartments of the transmission is the torque converter. When full, the fluid level of the torque converter is much higher than is the level of the pan (almost entirely above the pan in most cases). Due to this, when the engine is stopped, a significant amount of the fluid will drain down into the pan, showing the wrong amount of fluid on the dipstick. With the engine running, not only is the transmission paths filled with fluid, but the torque converter is as well. Then a check of the fluid will give you a proper level.
Checking engine oil is a lot different. It needs to be checked when it's in the oil pan. In order for it to be in the oil pan, it needs to drain after it's been up in the engine. This takes a little bit of time. Engine oil doesn't expand as much as transmission fluid, so can be checked hot or cold. While engine oil is important to how an engine operates, the level isn't as imperative as transmission fluid. Transmissions are very sensitive to line pressure. As you get more transmission fluid into the transmission, the pressures rise. If left unchecked, the fluid will find an escape hatch somewhere and that somewhere is usually a seal. Blowing out the front main seal (or where the torque converter rides) requires a transmission pull to fix. This isn't something you want to do every day.
Engines don't have the pressure effect which transmissions do. The pressure is regulated at the pump and mainly needs to have oil flow in order to operate efficiently. Most engine manufacturers are good down to even 5psi of oil pressure. There is also a lot of space in an engine for oil to hide. As oil gets pumped around, it sticks to walls and is all over the place. It needs to drain back into the sump, thus the 5 minutes of drain time. Not everything will drain down, but the vast majority of it will. This isn't how every manufacturer likes to have it read, but leaves things in a pretty good state as far as the level goes.
I don't read this as a discrepancy in either case. I look at it as how they are designed/engineered to be checked.
If your vehicle is experiencing any issues, such as hesitating when it shifts gears or if it makes noises while shifting, you don’t necessarily have to get a new transmission. It could be as straightforward as just checking your ATF, or Automatic Transmission Fluid.
Your transmission depends entirely on this distinctive fluid, hence a low fluid level can have a disastrous effect on transmission operation. We recommend you check the level at least once a month. This will enable you to catch a slow fluid leak you may not know you had potentially saving a lot of money in damaged transmission parts. Your car’s owners manual should provide a detailed description on how check your transmission fluid level. If you don’t have an owner’s manual, here’s the basic procedure that will work on just about any car that has a transmission dipstick.
WARNING: Checking the transmission fluid level requires working under the hood of your car with the engine running. This can be very dangerous if you aren’t careful. Watch out for moving components, such as fans, fan belts, pulleys, etc. If you aren’t comfortable with this procedure, always take your car to your local service station to have the transmission fluid checked.
- Make sure your car is on level ground.
- Start the engine (and don’t turn it off until finished!)
- Bring the engine and transmission to normal operating temperature.
- Hold your foot on the brake, and work the shifter slowly through the gears.
- Put the shifter all the way back into park.
- Set the parking brake.
- Carefully open the hood.
- Find the transmission dipstick.*
- Remove the dipstick, and wipe it off with a clean rag or paper towel.
- Slide the dipstick all the way back down into the transmission fill tube.
- Pull the dipstick back out, and check the fluid level against the markings on the end of the dipstick. (It should be pinkish & almost clear but if it smells burnt or has particles in it, have a mechanic drain and change it).
- If the transmission fluid is clear but doesn’t reach the “Full” line on the dipstick, use a funnel to pour just enough transmission fluid down the dipstick tube to reach the line. Don’t overfill!
REMEMBER: Always use the fluid recommended by the manufacturer (see ‘Choosing the Right Transmission Fluid’). Also, if the transmission requires more than a quart, or is using fluid regularly, take your car in to have it checked for leaks.
If you’re ever unsure of the procedure or where to find the transmission dipstick, check with your local Mister Transmission shop. They’ll be happy to show you where the dipstick is, and how to check the fluid level.
LASTLY: Unfortunately, in recent years, many manufacturers have started to eliminate the transmission fluid dipstick. Referred to as sealed units, these transmissions require a much more involved process to check fluid levels than in days gone by. The process often involves electronic testing devices, such as a computer scan tool. This puts checking the transmission fluid level beyond the capabilities of the average car owner. So if your car doesn’t have a dipstick, you should have your local transmission shop or dealership check the transmission fluid level at least a couple times a year, even if you don’t notice a problem with transmission operation.
A FOOTNOTE: It’s also worth mentioning that a faulty transmission and one that’s just low on fluid share many of the same symptoms. But obviously, adding transmission fluid is a lot cheaper than replacing the whole transmission system! Either way, we’re always here to help in any way we can.
*Rear wheel drive vehicles — the dipstick will usually be on the passenger’s side of the engine compartment, near the back of the engine.
Front wheel drive vehicles — the dipstick will usually be on the driver’s side of the vehicle, on either side of the transmission.
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- 15903 Stony Plain Rd. NW
- Edmonton, AB
- T5P 3Z7
- 587-786-6465
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