2011 Tundra with the 5.7 and 4x4. Truck sees mostly long trips with moderate towing. Current oil is Mobil 1 EP 0W-20. I put about 6-7k miles a year on it. Owners manual calls for 6 month or 5k mile oil changes (whichever comes first) and I followed that schedule while the warranty was in effect. Now that the powertrain warranty is expired should I just switch that oil change interval to once a year?