Interesting. Like others, I do my own oil changes (often) and always replace all the o-rings, and have never had a leak from the filter housing. I did have a problem with the crankcase vent covers leaking on the valve covers, and I had to remove and reseal them. I was rather surprised to learn that MB does not make or offer a gasket for these covers, so in my mind this is a straight up factory defect. In order to get a good seal I bead blasted the mating surfaces and used Permatex ultra black sealant. Seems to be working fine so far.