Briggs & Stratton engines typically recommend using high-quality detergent oil that meets or exceeds the requirements of the American Petroleum Institute (API) service classification. The most commonly recommended oil for these engines is SAE 30 oil for warmer temperatures, which is ideal for lawn mowers and outdoor power equipment operating in temperatures above 40 degrees Fahrenheit. For colder conditions, Briggs & Stratton advises using 5W-30 oil, as it offers better performance in low-temperature environments. Additionally, synthetic oils can be used if they meet API service classifications. It is always best to refer to the specific engine owner's manual for the appropriate oil type and viscosity recommended for your particular model, as requirements may vary. For detailed information specific to your engine, one could visit the official website for further guidance.