According to Stu Ritter’s book, if the car is parked for a week or more, the ATF in the torque converter may drain back into the transmission housing. Then the ATF may run out of the front input seal.

I want to know whether my ATF ran out of the front input seal. Where is the front input seal?

I did not park my car over a week or more, but I parked my car for five days in the early January.

I checked the ATF level a few days ago. I had to put 400 ml to have the level between min and max. I did that after driving 50 minutes (not on highway, not in heavy traffic jam) so that the transmission is at normal operating temperature. The coolant gauge was between about 85 and 90 as usual. The ambient temperature was about 40 degrees F.

The last ATF level check was only three months ago; 400 ml loss in three months is quite a large loss.

1992 300D, 303 k miles. 722.418

P.S.
I did not have any puddle below the car. There is vinyl covered sponge on the black plastic noise shield panel below the transmission. The vinyl in my car is torn, and the sponge absorbs the ATF and releases the ATF slowly.

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.