I have a two year old Tundra with 20,000 miles on it. I was surprised that Toyota only recommended 5000 mile changes, as I was raised to believe that 3000 miles was gospel. I usually get it done around 4000, which is just a little more frequent than 2x/year. I've never specified any type of oil, figuring they'd Know best for my climate, which is warm to hot in summer and Dang Cold in winter. also have a garage queen Miata, stored inwinter, driven only in warmer weather.any special recommendatons for either of these vehicles?