In our two '99's we are running Mobil 1 5w-30 truck and suv blend; up from Mobil1 0w-30 and are getting quieter and more peppy performance. They both cost the same $21.38 for a five quart container that makes a handy dirty oil repository after you change it. This seems to be a good summer oil alternative. I will keep you posted on the mileage which is running close to 20mpg, but we're talking summer temperatures here and that always is better for mileage than winter.