As I understand, you want to check transmission fluid at operating temperature or about 180*F. That’s the temperature of the fluid, not what’s displayed on the gauge as engine temperature. You won’t get transmission fluid to that temperature idling the engine. Probably not an OM616 with a good cooling system either. I take the car on a 20 mile drive, that’s somewhere 20 miles away from the starting point, not 10 miles to the store, look around, the 10 miles home. Leave the engine running, transmission in Park, pull the dipstick, make sure the fluid is too hot to comfortably leave fingertips pinched on the wet end, then check fluid level.

Once that’s set, check it cold. Start the engine, run through the gears making sure each setting engages, them check the fluid level. I have this cold baseline for a weekly check since I can go weeks without wandering 20 miles from home. The cold baseline gives me a target after fluid and filter changes although the FSM tells you how far below the min level it should be before a test drive.

Problem #2 is different readings on the faces of the dipstick. Techs told me they average disparate readings. I’m tempted to drill small holes at the lower and upper lines. There’ll be fluid in the holes or there won’t.

Sixto
98 E320s sedan and wagon