Did you run it long enough to heat the ATF to 80 before checking the level? And was it OK then at that point?
To be truthful I cannot say I ran it long enough to reach 80 before checking the oil as when the car was stationary on Sunday I started the car and left engine running until the temp reached 80 but then it was raining so I didn’t open the hood and test however later when rain stopped, the engine was switched off for approx 20mins or so, I checked the oil with dip stick and it was close to the top 80 on the dipstick gauge.
Today’s update: from 1st to 2nd gear the car changed gear perfectly smooth but on third gear I heard a grinding noise for few seconds followed by a boom boom sound (as if you blow in a empty metal pipe, it’s not the exhaust as I have a brand new Mercedes original exhaust pipe fitted) - that sound was for few seconds and then when the car picked up speed that sound went away. the car drove perfectly fine from 60mph to 80mph on motorway but as soon as I slowed down I heard the cog noise (grinding) again for few seconds and then it went away again.
My worst nightmare (hopefully not), Could this be a problem with coolant or God forbid water made its way to transmission via broken/crack pipe or TC or Gearbox gone? I am not entirely sure but it does look to me the issue is worst especially the new discovery of grinding noise even for few seconds. For now am sticking to oil change but also ordered solenoids. Once get them delivered and possibly change them this or next weekend.
Kindest regards
Jehanzeb