what weight oil do you use? is it syntehtic? have you checked the actual oil pressure guage? 1 quart over 3k miles is not negligible for a benz.
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)