Most of the MB engines hold ~7.5 L (7.9 qts) in the pan and an additional .75 L (.79 qts)in the filter.
When you pour your 2 gallons of oil in after the oil change, the filter will fill when you run the engine. That's why you're about 1/2 a quart low on the dipstick. As long as your level is between the min and max marks you're good to go.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.