Take a look in the DIY 35d Oil Change thread for a description w/pictures, of how to remove the plastic air tube. You can check the oil without removing the air tube. But is helps the first time.

FWIW the easiest way to pull the dip stick, when the air tube is installed, is to just pop the dipstick loose with one finger on two different hands (i.e. reach under the air tube with your right hand). Then you can easily pull it the rest of the way out with your right hand while holding a paper towel to wipe the dip stick with your left hand.

Funf Dreisig