I have a 2004 Buick Park Ave (3.8) that got 3 or so months ago. I bought Valvoline Restore and Protect oil to hopefully clean the motor. I tried to take the drain plug off but could not. The P.O. had a place close to my work do it and its a oil change place. Had my own filter (AC Delco) and new drain plug also. Will see how it will do. My 1st time there and hopefully only time. They asked if i wanted something put in to clean the motor. No i said. The oil suppose to do this. I also kept the old filter and drain plug it was rounded. I plan to change the filter in 500 or so miles.