Automatic transmission fluid level

#1

Hey! Good morning folks . . . I have an automatic transmission related question. I know that you should check the fluid warm, on a level surface and that you should smell it and check the color and all that. But what would an automatic transmission fluid level be COLD? Above the warm? Below? Am I correct to check it warm? (Owners manual says to do so). Reason: We changed the motor on my wife’s 95’ Civic (bad wrist pin)two months ago and the salvage yard motor had about half of the mileage that ours had on it, for $600, runs fine, changed the oil twice already at 1000 mile intervals. But I never serviced a tranny before, always took it to the local transmission guy for fluid changes (at 30, 60, 90, etc). Over the holidays he had a heart attack (doing OK, BTW), and I started checking the fluids after the engine change every day, and I don’t see any difference in warm or cold fluid level of the automatic. Should there be? Rocketman

#2

Yes. The fluid expands a bit when it’s warm, so the level should be a bit higher on the dipstick when warm than when cold.

Some transmission dipsticks have a “cold” and a “hot” range marked on them. It’s best, however, to check the transmission fluid level when the transmission is at normal operating temperature, as indicated in the owner’s manual.

#3

Thanks McP . . . this dipstick only has two lines, apparently a low and a full, but I’ll keep an eye on it. Rocketman

#4

I think the normal recommendation is that it is best to check it when hot - after a good drive of decent duration (20mi or so). I always do mine hot. I thought all trans dipsticks had marks for cold and hot - but if yours doesn’t I would guess that checking hot is the best option.

#5

If there is just a high and a low, check it when hot. If you add fluid when it is cold, you might add too much. A GM turbo 350 would sometimes not upshift if there was too much fluid IN COLD WEATHER. The fluid would be higher than the modulator valve and that condition would cause a shifting delay. Without a modulator valve, the level may not be critical.