I would like to point out to Toyota owners that it wasn't that many years ago that Toyota had a major sludge build up problem on the 3.0L V/6 and 2.2L 4-cyl engines which began right after they upped their recommended oil change interval to 7500 miles. There have been many owners who stuck with the old 5000 mile change interval and never had the problem, myself included. Subsequently, they went back to the 5000 mile recommendation (which they have since gone back on) and installed a 5000 mile oil change reminder light. The problem went away. IMO, unless the majority of it's miles are on the highway, I would stick with 5000 miles.