Disappearing and reappearing transmission fluid 01 Camry
 

2001 Toyota Camry
105K miles
4 cylinder
Got car from family member at 80K, previous reports of proper maintenance turn out to be wrong. This may be first trans fluid change (@ mile 105 K) ever.
Current problem:

Confused about transmission fluid level so I'm not driving it for now.
When cold, fluid shows as too high (too high makes some sense if you read background below). It's a bit below the "hot mark" on dipstick when cold. Fluid is very obvious, very easy to see, clearly demarcated on the stick. Not so when hot which is the reason for this post.

When running the engine and checking at 2, 5, and 10 minute intervals, fluid can be observed with each check growing increasingly thin and the stick ends up DRY with only the slightest very thin streaking along the very edge of the dipstick. Where is it going? It does all drain after car is off. I can repeat this process and have done so over several days.

Comparing to my sons 2003 Corolla, his car- the fluid is nice pale red, in the appropriate "cold" spot on the dipstick when off and then moves up the stick to the appropriate "hot" zone over several minutes of running the car. All very visible, very good coverage of the stick, nothing looks dry at all, clearly demarcated. Total opposite of my issue.

Question is why would there be too much fluid when COLD and then it all seems to vanish when HOT ? Shouldn't it simply move way up the dipstick vs disappearing?

BIGGEST FEAR is that too much fluid caused fluid to bust through something when hot, maybe going somewhere it shouldn't and it's unable to stay in ciculation. I don't know enough about cars to know if this is even a real possibility.
Do additives interfere with reading fluid when hot?

I did check for trans fluid in coolant reservoir, below radiator cap, underside of engine oil cap, engine oil dipstick and have been looking at the trans dipstick (obviously). None of these show signs of contamination. Except for the trans fluid which was black before my change, seemed to get marginally lighter after the change and has returned to black unfortunately.

Background:
Dropped the pan and replaced filter, pan back on. Mistakenly put only 2 quarts of trans fluid in. Drove 30 miles around town and there was slippage. Added 1/2 bottle of Lucas Trans Slippage Product. Then realized I was a short on actual trans fluid so added it. So that is why it registers as high, I guess. Drove for 3 weeks, rare slippage and was mainly going from reverse to drive but prior to change there had been zero. Never observed any fluid on the ground after the change, I was looking for any that might drip out. Pale concrete nice and clean. Checked fluid a few days ago because I had nagging doubts and got the current problem described above.

Any ideas? Thanks!!

Was the trans slipping prior to the pan fluid change?

Most of the fluid is in the torque converter and doesn't drain out on its own.

Drive car to get trans fluid hot. Engine running, move gear selector from P to L and back again pausing in every gear.

Engage emergency brake. Engine on with trans in P check fluid using Hot High/Low marks. Keep wiping the dipstick clean of fluid until you get a clear and consistent fluid level mark.

The difference between full and low can be minimal as in ounces of fluid. If low don't add too much before rechecking. If checking or adding fluid the dipstick tube walls can have fluid on them making the stick reading less clear.

Suggest if going to keep the car to change all the trans fluid. This can be done by disconnecting the trans oil cooler return line to the trans. Drain and fill the trans pan with new fluid. Start engine and let about 2 quarts of fluid flow out from the disconnected line into a container. You want to stop the engine BEFORE the fluid stops coming out in mass.

The internet has posts on how to do this.

Refill pan with new fluid and repeat the process until the fluid coming out is clear. This may be 8 to 10 quarts.

Trans additives may not be a good thing and could make things worse then better. Suggest sticking to trans fluid only.

Thanks. I will do all of that, though I am worried about flushing since that could cause slippage now. Do you think it could? First ever trans oil change at 105K miles. It was never slipping before this change. Black fluid etc.

Do you have ideas about why there is plenty of fluid on the stick when cold but as it heats up the stick goes mostly dry? That seems impossible unless it's going somewhere it shouldn't and getting lost (but that doesn't explain how it returns to normal when cold). Should I ignore cold readings and only go by hot? I had thought if it showed too much fluid when cold (level was up around "hot" region") that was proof not to add more. Maybe I'm wrong.

Not a flush. Just remove the old fluid using the trans oil pump and fill with new.

A pan drain and refill is approx 1.6 qts. You added 2 quarts + the amount in the bottle. The trans is now apparently too full of fluid which could cause slipping.

Too full may make getting a good dip stick reading difficult.

If you want to, drain the pan and add back 1.5 quart. Use the cold marks if fluid is cold. Best to have the fluid slightly low when cold and top off when fluid is hot using hot marks.

Added chemicals may cause trans debris to break loose which can cause more problems then the chemicals are stated to solve.