2005 Mercedes Benz E320 change Oil

The drain plug is located on the oil pan. I believe it faces the rear of the car. Also, some of these have an internal oil filter cartridge. Have you located that?

you need to remove the lower panel bolts which are a 8mm socket size. drop the panel down and the drain plug is 13mm.the filter is is a plastic housing on top of engine be sure to replace all the oil rings on the filter carrier.good luck.