Transmission Fluid Full When Cold, Low When Hot. Is This OK?

A car's transmission fluid level is affected by certain factors such as weather, vehicle temperature, presence of leaks, etc. Temperature, for instance, will affect the accuracy of the results of a trans fluid check. The results for hot and cold trans fluid can't be the same.

Fluid level check highlights

• Level of importance:High
• Time interval:Once every 6 months
• Needed expertise:Basic
• Needed tools:None
• Time taken:5-10 minutes
• Possible issues:Transmission failure, problems with torque converter, jerking, overheating, slipping.

Essence of Transmission Fluid in Your Car

Your transmission fluid is just as important as the engine oil in your car. The vehicle won't be drivable without both in it-in addition to other fluids like brake fluid, fuel, Haldex fluid, etc.

Transmission fluid is very important to the proper workings of a transmission system. There'll be problems with shifting, overall vehicle control, and so on if trans fluid isn't adequate or in good condition.

Trans fluid should be well-maintained just like the other vehicle fluid types. And one of the ways you can do so is by checking the fluid levels routinely. See how to perform this important check in the next section.

Avoid pouring automatic transmission fluid (ATF) into the engine oil tank to get rid of sludge. It will negatively affect the oil's viscosity and wear protection properties wherever it's supposed to reach. Fuel efficiency will also be adversely impacted as well.

How To Examine the Transmission Fluid Level in Your Car

Your car's transmission fluid levels should be checked at least every half of a year. Do it more frequently in locations that have hotter climates.

Avoid recent model-year vehicles that don't come with trans dipsticks. In other words, they're referred to as sealed-for-life transmissions with fluids that aren't meant to be changed. This makes the DIY checking of the fluid's level not possible.

You'll have to take the car to an auto repair shop for anything related to a transmission check. The mechanic will conduct a fluid level assessment via a plug situated on the transmission's side or by looking at the vehicle's computer.

The dipstick of the transmission fluid bears some similarities to the engine oil's dipstick. They both perform the same functions in their respective containers. A transmission fluid check with a dipstick will help you to ascertain if there's a leak, a need for a top-up, or a reason for a flush. See the checking process below.

Step 1: Park the Vehicle

Do this on a level floor or surface then open the hood of your car. This will help to ensure that you get precise results during the assessment with a dipstick

Step 2: Warm the Car

The vehicle should be "on" and left in "park", then you can let the engine run for some minutes. You'll be doing this to warm the car (transmission) up to ensure that you get an accurate trans fluid level reading. The engine will still be running even as you examine the fluid's quantity.

Shift the vehicle through all its gears (first through reverse) at least twice to ensure that the transmission's valves and passageways are totally filled.

Note: Honda is the only automotive manufacturer that advises its users to switch the engine off and quickly check the fluid's quantity.

Step 3: Find the Trans Dipstick

You should be able to see it near the oil dipstick in cars with front-wheel drive and near the back of the engine in cars with rear-wheel drive. It should be labeled for easy recognition and can feature a pink, red, or yellow handle.

Pull the dipstick out of the transmission fluid's reservoir and clean it. Get a small towel or rag for this job. Wipe all the traces of fluid from the dipstick or just make sure that the stick is clean.

Step 4: Take the Fluid Level Reading

Put the dipstick back into the trans fluid tank to get the level reading and remove it again. Assess the fluid level by looking for where traces of it stop from the bottom to the top of the stick. Look for markers such as "full" or "low" to ascertain the result of the procedure.

Step 5: Refill/Top Up

Put the dipstick back if the quantity is "full". If not, refill the reservoir or top up the fluid till it gets to the right "high" level. Some cars that have markers for checking the fluid amounts when the vehicle is warm and cold. You should look out for such cases or consult the car owner's manual to understand.

Other Things To Note About Fluid Levels

A low fluid level may be pointing at a leak. The leakages will need to be investigated further by a mechanic. Doing this examination yourself isn't advisable.

A frequently low transmission fluid level means that there's an internal leak that can't be easily detected. For example; leakages in the radiator, bell housing, transfer case, etc. A mechanic would have to conduct a thorough trans check. Such an abnormal occurrence isn't due to evaporation.

You should also be cautious during a top-up or refill so that the tank doesn't become overfull. This is because such an occurrence can cause fluid foaming and apply too much pressure on the trans. It will force the fluid out of a seal or the vent, leading to gear slipping and unstable shifting.

Another good way to confirm that the fluid is at the right level is to wait for some minutes for the engine to continue running. You'd have to insert and remove the dipstick again for a final reading. Replace the dipstick and close the reservoir with the stick's cap after the procedure is done.

Cold checks aren't usually needed. The only reason the dipstick marker for the cold level may be provided on some vehicles is because of manufacturing requirements. It's to ensure that they fill the trans fluid to the minimum level to protect the torque converter from sustaining damage when the car first starts up.

What To Look Out For During a Transmission Fluid Check

• Scent

Trans fluid should be virtually odorless when it's clean. So you should be worried if you get a whiff of a burning smell from it. This might be a transmission fault symptom that needs to be addressed as soon as possible. The fluid may also be black due to burning. Read more about trans fluid color in the next subheading.

• Color

Most modern trans fluids are bright red with a transparent look. The color will become darker and less transparent as time passes, so you shouldn't be worried about seeing a brown tone. However, seeing a black fluid is a symptom of bad fluid that should be swapped out. It could be a sign of burning, as stated earlier.

• Consistency

Time and usage will make the fluid thicker than normal. But this is OK as long as it isn't black or has metallic pieces (shavings). Apart from overfilling, foaming could be a result of overheating or the wrong fluid being utilized.

Why a Transmission Fluid Flush May Be Necessary

You should flush out the fluid if you want to check its color and content properly. For instance, dirty fluid and metallic pieces of transmission components. The internal parts of the transmission won't have the adequate lubrication they need to work well if the fluid is dirty or obstructed by a clogged/blocked filter.

Flushing out or draining will expose contaminants or abnormalities that can't be observed well with the aid of dipsticks. Although it's possible to know how transmission fluid smells from drops of it falling off the dipstick.

It's advisable to swap out your transmission filter after replacing the fluid. The vehicle owner's manual is supposed to state this. A new trans fluid and filter should result in renewed optimal trans performance without issues. Transmission flushes should be done on the attainment of every 30,000 miles.

Auto repair shops use flush machines to get rid of the old fluid and put in the new fluid. Ensure that they evacuate the reservoir so that there are no remnants of the old one. This is because the remnants can contaminate the new fluid if care isn't taken during the swap.

Conclusion

Knowing the quantity, color, and smell of your transmission fluid regularly will help in maintaining it properly. You'll know if it needs to be topped up, flushed out, changed, and so on. Routine maintenance will be good for the fluid, the trans, and the overall operation of the vehicle.

So no you know what a "hot" or "cold" trans fluid entails and which is best for the checking procedure. Try your very first DIY trans fluid check with the steps described in this guide instead of paying good money for it!