I've always changed my own oil and I'm a big believer in getting rid of the dirt with more frequent oil and filter changes. I change mine every 2,000 miles when the odometer rolls around to an even number. What convinced me to change that often was when I changed my daughter's oil when she would run it 3 or 4,000 miles. I use an old white refrigerator pan for my drain pan and you would not believe the sludge difference between 2,000 mile oil and 3,000 mile oil. I ran Amsoil in my old truck back when vehicles had carburetors and I did an oil analysis at 10,000 miles. The oil was full of fuel dilution, carbon and what ever bearings are made from. Back then it was a diester based oil and it ate through the seals, so that truck leaked from everything where I had Amsoil. I ran Mobil 1 synthetic oil in a turbo charged Saab when it first came out when it was pretty thin at 5w20 I think it was. It did keep the engine very clean, but I replaced two turbochargers at $750. each because the seals went out. That was not an inter-cooled turbo, but since those turbo shafts ran on an oil supported bushing, I've always blamed the thin Mobil 1 oil for the failures. I figure that today's long oil drain intervals are brought to you by the same manufacturers that want you to buy another new vehicle. I was talking to a cab driver in NYC and he told me that they change their oil every week.
