When to check Trans. fluid?

[Oldcountryboy]

I know your not suppose to check while cool, but just exactly when. I'm getting two different readings on deisal truck. I'm letting it warm up for 30 minutes but not driving it in that 30 minutes. When I check then I get a different reading then when I check after about a 2 hour drive.

30 minute no drive results in needing to add a little bit of fluid.

After 2 hour drive results in over fill. The fluid level is up above the full mark.

So what's the proper way to check it? I'm thinking the no drive method is not letting the fluids warm up enough.

[OkieDavid]

I always check mine on level ground with the engine at operating temperature, sometimes I've been on the road and I'll check it during a fuel stop other times I'll check it before a road trip by just letting it reach operating temp via idling in the yard. Shouldn't make any difference beyond making sure you're on level ground?

[Old Vet]

It should be at operating temperature. When you check it at low temperatures the oil will not be thin enough to get through the gears before you check their fore it will check low. If it uses a lot of fluid you will probity have to check it every time you drive it but if not then once a month will do fine.

[Danaus29]

We always check ours after a short drive. Make sure you park on level ground.

ETA, for us a short drive is 15 minutes or longer.

[Oldcountryboy]

"Engine at operating temperature".

This is where I'm confused at. I'll let it warm up for 30 minutes and then check it and will get a low level reading on the transmission dip stick. After driving it for a couple of hours I will get a high level reading.

I'm thinking that warming the engine up for 30 minutes isn't doing anything to warm the transmission oil up and this isn't giving me a correct reading. I maybe wrong cause I don't know what goes on inside a transmission when it's setting in neutral. Is the pump pumping transmission fluid when the transmission is not in gear?

Is checking the transmission fluid after a two hour drive giving me a more correct reading?

[tamsam]

I don't know what truck you have or how much fluid it holds. Some trans don't pump the fluid unless in gear so it does't heat the fluid. After driving the fluid is hot and has expaned so I would say check after driving. Hope this helps. Sam

[foxtrapper]

The engine can be cold as a stone, the thing that has to be warmed up is the transmission. And, the transmission has to have the fluid pumped throughout itself.

The standard drill is to drive the vehicle for a while to thoroughly warm it up. Then run the transmission through the various gears, then put it in park and wait a moment. Check it.

[zant]

Engine must be warm,level, and running when checking trans fluid.Also religiously replace filter(s) and fluid EVERY 30k...

[Wis Bang]

Originally Posted by tamsam

I don't know what truck you have or how much fluid it holds. Some trans don't pump the fluid unless in gear so it does't heat the fluid. After driving the fluid is hot and has expaned so I would say check after driving. Hope this helps. Sam

Way back [early 70's] I replaced the filter in the auto trans of the owners Olds. The instructions [GM replacement filter] were specific about how much oil to use when re-filling the trans and then specified driving a set number of miles b/4 checking and topping it off.

They said you had to let the new oil reach operating temp and expand so you did not overfill the trans...

I'd drive it b/4 checking. Look at the owners manual, most GM and Fords want you to cycle slowly from Park thru each gear to Low and back which makes the oil flow thru every section of the valve bodies...

[Beeman]

Trans must be at operating temp, engine temp doesn't matter. Best checked on level ground and in the appropriate gear selector setting as specified by your vehicle, don't assume park read the dipstick or the book. Also be sure to use correct fluid as there are quite a few different ones out there.

[scott]

Originally Posted by Beeman

Trans must be at operating temp, engine temp doesn't matter. Best checked on level ground and in the appropriate gear selector setting as specified by your vehicle, don't assume park read the dipstick or the book. Also be sure to use correct fluid as there are quite a few different ones out there.

what beeman said.... my 97 dodge van HAS to be running and in neutral to get a correct reading ...if it says full and your in park... your actually a quart low.

[How Do I]

I've always checked mine after driving. Usually after a drive to the nearest gas station. About 25 minute drive. Just took it for granted (check after driving) because that's how I learned.