When I check the transmission fluid level on my C280, I get various readings. The car is at operating temperature, is idling in park, and is on level ground. However, when I check the level, sometimes it shows at the cold level mark, sometimes a bit higher, sometimes only on one side of the dipstick, sometimes it seems to be spread up the dipstick like it was running down the stick, and sometimes there is a gap between the traces on the stick. This has been very frustrating and I certainly don't want to overfill and create problems. However, I don't want to underfill either. Is there some magic trick to getting this right?