When checking trans fluid: leave car running, or turn it off?

Question

I was just checking the automatic transmission fluid on a friend's car, with the engine running, when he said I should turn the engine off. I thought when you check the ATF, the engine should be running, and after a 30-minute drive, after having gone through all the gears. Or, must the engine be off?

Answer 1

Engine running, fluid hot.

Answer 2

2

Answer 3

Engine running with fluid in transmission hot. Drive it around a bit first. Transmission fluid expands when it is hot. If you check it when it is cold you could over fill it. This could cause to much pressure in a transition ( you can not compress a fluid) causing expensive damage.

Answer 4

it is amazing how many people answer this not knowing what kind of car it is. Most cars it would be engine running in park, some are neutral, some are engine off after running. it is true that most are marked on the dipstick

Answer 5

car needs to be running. Transmission fluid is very thick

Answer 6

engine must be running for several minutes. going through all the gears is not necessary

Answer 7

whenever you check transmission fluid the car must be running.

Answer 8

trans fluid check at normal op temp in (N) and check your oil before you start the engine

Answer 9

read you manual, its there
Normally, its have the car running at normal temperature in park
There used to be some that required the trans to be nuetral, but I don't think those exist anymore.

Answer 10

hidi ho .you must have engine running to check fluid level [because] trans.have a pump in them that run off of the turning of the crank shaft. You are welcome.