Skip the auto shop - Our mechanics make house calls

Q: How do you accurately check your automatic transmission fluid? Hot, cold, running, put all gears through, then check?

asked by on

transmission fluid check, see above Thanks

A: Typically, the fluid level is checked both ...

Typically, the fluid level is checked both hot and cold in order to provide a cross check. Checking initially when cold is easier as you are not hovering over a hot engine holding a hot dipstick. Basically, on a flat level surface, start the vehicle’s engine and immediately run through each gear, pausing just momentarily.

Finish with the car in "Park" and leave it in "Park". Withdraw dipstick and wipe it clean with a LINT FREE cloth (lint and dirt causes problems in transmissions). Reinsert the dipstick after you have wiped it and upon withdrawing it. See if the fluid level is within the cross hatched area marked below a "C" (for cold).

Sometimes you have to look at BOTH sides of the dipstick in order to gauge the level. If the level is in the "C" area, you are likely OK, but to be sure, drive the car for about 10 miles and re-check the level, this time looking at the cross hatched area marked below the "H" (run through gears as before, and leave in "Park").

If the fluid level is OK when cold, it should also be within the cross hatched area for "H" as well. The reason for checking when both hot and cold is transmission fluid expands as it is heated. Note that if you drive the car at highway speed for a long period of time and then attempt to check the fluid level "hot" after that you WILL get a false reading (the fluid level will appear "high", when in fact, it is perfectly OK). So, when checking if it’s hot, you can’t do that check if you just drove 50 miles across the desert because the fluid will have expanded. Transmission fluid expands and keeps expanding the hotter it gets. Dipsticks are calibrated to "normal" hot operating temperature (i.e., the 10 mile suggested drive; longer in winter). If the transmission fluid has been in your vehicle for more than 100,000 miles, change both the fluid and the filter, which maintenance will help promote the longevity of your transmission. Modern synthetic transmission fluid of the right type is recommended. If you are in need of a transmission fluid service, a certified technician from YourMechanic can come to your car’s location to perform this.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: My thermostat needle goes to hot, but the car does not get hot. Is it the thermostate?

This can be caused by a number of things such as low coolant levels, a faulty thermostat, or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning...

Q: My car jerks when decelerating from what seems to be 4th gear to 3rd.

You need to have the codes scanned by a professional with a scan tool for the transmission computer. The codes may give you an indication if the sensor is not performing correctly. If it is not a sensor malfunctioning (like...

Q: No dash lights or gauges

Hello. The existence of so many non-functioning items would seem to indicate that a main control fuse, and junction box, are not working. Check to see if there are any electrical components that may have been disturbed during the timing...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.