mmo

note: 2000 ford ranger 2.5l 2wd mt, 275,000mi, i received the truck at 120,000mi .... i have gone quite a few oil changes to over 5k miles and/or over 10mo Hey, I am wondering if it is a bad idea to place Marvel Mystery Oil in my high mileage engine? i have never "de-sludged" my engine before...