Quick question, We took a drive yesterday about 75 miles one way. I pulled off after 25 miles to recheck the trans fluid. I pulled into a gas station parked and left the engine running when I looked at the level it was showing only up to the top of the C on the stick so I added a small amount of fluid.
This morning I checked it again cold, have not even started the engine. The fluid level at this point is at the very top of the dimpled part where the plastic and metal meet.
That tells me when I checked it and added fluid it really didn't need fluid, wondering why it showed low on the stick?
Any help is really appreciated.
I'm going to remove some fluid while still cold before I drive it today.

 

Automatic transmission fluid level is usually checked on level ground, warmed up and with the engine running.

Anytime you ask anything, you should tell us the year, model, engine size and type of transmission so we can give better answers.

 

What was the small amount of fluid? 25 miles of easy driving might not get ATF very hot. My rule of thumb is ATF has to be uncomfortably hot on fingertips to be at operating temp. My ScanGauge II says it takes 50 miles of easy highway driving to get to 130-140*F which Mark K says is hot enough to register properly on the dipstick. IIRC at 25 miles it barely registers 120*F. For reference, we have a 4R75 with factory ATF cooler. There's a recent thread about checking the dipstick. Basic guidance is if ATF registers in the knurled area, don't add fluid.

[edit] @MojaveRed , you're on that thread I mentioned.

Sixto
07 E350 5.4 200k miles

 

Doing that will ALWAYS show the level higher than what it really is. Don't EVER do this.

Because it didn't have enough fluid. Checking it cold, and especially with the engine off, will ALWAYS give you the wrong result.

 

Thanks everyone,
etinpa, thanks for the tip on including my type of vehicle. I have put that info as my signature. 2012 E350, 504L, 130K, 4R75E.

tabijan, Thanks for the info, not sure what the temp was when I checked it but the first 25 miles were on the freeway at 65mph. I like the idea of making sure the fluid temp is between the 130-140 range before checking it. Seeing how Forscan is free to use I put it on a laptop and checked it yesterday after a short drive to check the fluid. It said the fluid was at 131.

Mark Kovalsky, Thanks for all your help on this. I thought I knew more about automatic transmissions but I'm learning a lot more than I thought I knew. I will never check the fluid again while it's cold. I did some research and now understand (hopefully) that the fluid from the converter and trans drain back into the pan after sitting overnight, hence the over full reading. I will be adding fluid today after I let it warm up then drive it a short distance to try and get the temp up. I'm still a bit confused as to why the reading was low after the 25 mile drive at 65mph.

 

Mark K can confirm but my guess is there’s as much as 20mm change in dipstick fluid level from first start to operating temp. Consider that if your transmission isn’t leaking externally or into the engine cooling system, differences in dipstick readings are caused by measurement procedure rather than fluid volume. As a matter of procedure, I check at the end of longer trips and assume it doesn’t change while parked.

Sixto
07 E350 5.4 200k miles

 

I've seen more than a 20mm difference. Some transmissions drain more fluid back than others when the engine is off.

 

Thanks tabijan, I don't think there any leaks into the coolant system but I will be checking that now just incase. I let it warm up today and drove it down to the local gas station about 4 miles. The trans temp was at 130 then so I added some fluid, drove it around a few blocks and checked it again. Did this several times adding about 2 oz. each time. It finally showed up on the dip stick just below the H like the picture I included on the other post, I checked the temp after seeing it at the right level it was 140 so I'm happy with that now. I guess I took out more that I thought the other morning as I ended up putting in about 12 oz. today to get it where it should be.