The Briggs & Stratton 5500-Watt Recoil Start Gasoline Powered Portable Generator typically uses SAE 10W-30 oil, which can be either conventional or synthetic. This oil type is suitable for a wide range of temperatures, ensuring smooth operation of the generator's OHV engine. If you're in colder climates where temperatures drop below 40°F (4°C), you might consider using 5W-30 oil for better performance