Hi all. On my '03 E500 722.6 trans I check the transmission fluid with the Febi dipstick #38023. By all accounts this is the correct part#. I check it hot after running it for @:30min. When the dipstick is pulled out, it seems to measure correctly topped off on one side, but smeared and spotty wet/dry on the other. Can anyone comment on this?

One side is getting scraped clean as you pull it from the dip tube.

Ahhhh! I'm going to try to twist it a few defrees before I pull out next time.

Don't get me wrong, I'm happy that a dipstick is available to measure trans fluid, but I'm having a love/hate relationship with it as I'm never sure of the level. Measuring hot, I can't see a clear-cut level line when I withdraw the stick. I understand that fluid will drip onto it on the way through the tube, and that the sides may scrape against the stick creating dry surfaces. Can someone throw light on this and how to absolutely determine levels?

Also, I understand that there's an overflow somewhere for excess fluid to exit. Does this mean if the trans is ove=filled it's ok and will be dealt with by the overflow system?

What happens to a trans that has been filled over the max?

No such thing as overflow system. There's a breather on top of the trans, but it's not for the excess oil to come out. You might confuse this overflow with 722.9 trans, which is filled from the drain plug. It would be really hard to overfill the 722.9 from there as the excess oil fill flow out as soon the filling tool is removed https://mbworld.org/forums/e-class-w...rain-plug.html

And your question about overfilling, it would cause transmission to run hotter, oil would get foamy and come out of mentioned breather.

Thanks. Learning on these cars never stops.

I just set my level yesterday. I ran a thermocouple down the tube as the instructions say it is much more accurate to read at 80 degrees C. I ended up driving the engine at 1600 rpm for a minute in drive with my foot on the brake to get to 80C. I then measured it in Park and idling, and added (and extracted as I went over twice) until I had it correct. It would be nice to measure it at 25C but ambient is hotter than 25C right now. It took several attempts to get it right as the difference between min and max seems to be a very small amount of fluid.

I spent a lot of time getting it right but found previously it is much quicker with a second person. BTW, I was just topping it up after replacing my radiator. The A/T cooler lines lose a lot of ATF fluid when disconnected. They also make a bigger mess than I was expecting.

Peter