Help! Dip stick proves transmission fluid is settling into pan.

[rustylog.]

After driving 2 months ago, my transmission fluid got near the "HOT" mark on the dip stick. Later that same day 2 months ago, after cooling, the transmission fluid was measured and it was near the top of the "COLD" mark. So, everything was fine.

Now 2 months later, the dip stick was checked and the transmission fluid measured 2-3/4 inches above the ''COLD" mark, which is 2 inches above the "HOT" mark on the dip stick. I turned on the engine and after 15 minutes I turned off the engine and checked the dip stick. The transmission fluid was now between "Hot" and "Cold" (much better). I restarted the engine and engaged the transmission and moved backward 4 feet and forward 4 feet. I was nervous to do more than that. Today, 3 days later, I checked the transmission fluid and it had creeped up almost 1/4" above "COLD" on the dip stick. I have a 4L80E transmission on a 1996 Chevy P30 chassis.

It appears that transmission fluid, normally stored in the upper part (i.e. operating portion) of the transmission, is now somehow slowly leaking downward and raising the level of the fluid on the dip stick.

1. Is what I wrote an obvious clue what is wrong?
2. Is this possibly an expensive repair?
2. Is it safe for me to drive the vehicle?

Thank you for any assistance.

[Soppy]

The transmission fluid should be checked after a drive with the engine idling in park.

[bigb56]

Like Soppy says you always check warm with engine idling. The fluid returns to the pan when not running and will read over full which is normal. If you examine your dipstick closely it might even say "check warm with engine running in park". At least your owner's manual will say that.
Easiest way I've found:
1. go for a drive to warm everything up good
2. park on a level surface and shut down for 20 min or so (this is to let the fluid that has sloshed on the dipstick tube to run down)
3. restart engine, pull dipstick and read/wipe, repeat multiple times, read both sides, one side will be smeared but the other side should show a clear line. Tilt the stick in different angles to see better. If the fluid is hard to see rolling the dipstick on a paper towel stretched out on your hand can help see where it is wet.

[Ray,IN]

You cannot obtain an accurate fluid level until the transmission is up to operating temperature. That means at least 20 minutes driving time.
The engine must be running to check fluid level. then follow this procedure: https://www.mistertransmission.com/h...mission-fluid/

[rustylog.]

Thank you Soppy, bigb56 and Ray,IN for your comments. bigb56, your comment: "The fluid returns to the pan when not running and will read over full which is normal." Boy, did I apparently worry for nothing. The thing that really made me worry was experience. I've been checking transmissions for 69 years and I don't recall seeing so much fluid in the transmission pan area. It must be I checked the trans in the past when it was warm or when cold, more recently turned off than I can recall.

Please note my owner's manual does not make any reference to bigb56's comment: "The fluid returns to the pan when not running and will read over full which is normal." So I have included what my Owner' Manual said on pages 4-26 & 27 below.

Thank you again guys. To help everyone my 1996 Chevy Owner's Manual states this:
"Checking Transmission Fluid Cold
A cold check is made after the vehicle has been sitting for eight hours or more with the engine off and is used only as a reference. Let the engine run at idle for five minutes if outside temperatures are 50 degrees F (10 C) or more. If it's colder than 50 degrees F you may have to idle the engine longer. Should the fluid level be low during a cold check, you MUST perform a hot check before adding fluid. This will give you a more accurate reading of the fluid level."

.Owner's Manual continues: "Checking the Fluid Hot or Cold
1. Park your vehicle on a level place. Keep the engine running.
2. With the parking brake applied, place the shift lever in PARK (P).
3. With your foot on the brake pedal, move the shift level through each gear range, pausing for about three seconds in each range. Then, position the shift lever in PARK (P).
4. Let the engine run at idle for three minutes or more. Then, without shutting off the engine, follow these steps:
A. Pull out the dipstick and wipe it with a clean rag or paper towel.
B. Push it back in all the way, wait 3 seconds and then pull it back out again.
C. Check both sides of the dipstick, and read the lower level. The fluid must be in the
COLD area for a cold check or in the HOT area or cross-hatched area for a hot check.
D. If the fluid level is in the acceptable range, push the dipstick back in all the way."

[GypsyR]

Key is "with the engine running". Checking the transmission fluid without the engine running is pointless. The exact opposite of checking engine oil. That gets people.

The "cold" reading is just a general guide. Before leaving on a trip it can assure that is at least a decent amount of fluid in there. And it gives you a starting point as to when to stop filling after a fluid change. But if you want to know that your transmission fluid is right on correct you have to check it hot. Many newer vehicles have temperature sensors in the transmissions and it's easy to monitor them. Having done so many times I can say that about ten miles is the bare minimum distance for a trucks and RV's to get up to operating temperature. I'm happier with double that many miles for a "hit" reading. Coming off the interstate for a mid-trip refuel is about the very best time for a solid hot reading.