B&S states that the optimum oil is 5w30 full synthetic and that is what I use in my John Deere 20 HP B&S twin and 2200-watt B&S converter gen set. It' fun to try to outguess the manufactures but, in reality they have the long-term data, and we don't. JMO. Ed
Read it again. Optimum engine oil for a Briggs generator is synthetic 15W50.
15W50 Vanguard oil- Varying temperature range. For continuous-use, such as commercial lawn cutting or pressure washing.
A generator is certainly “continuous use.” A air cooled Briggs/Generac generator used in Texas or Florida should use 15W50, per the manual.
I owned a small engine shop in Florida and I read the engine manuals from every manufacturer every year . Going back to 2000 or so.
For years it was just “Use SAE 30 or 10W30”. Then something happened. Briggs and Kawasaki and Kohler and others began blowing up engines on commercial mowers in Florida. 30 weight is NOT sufficient for a commercial mower in Florida. And then… the engine manuals changed. They added 40 and 50 weight oils, when before they just recommended 30 weights. This is what we call a clue. They got tired of warranty repairs on blown up engines.
As someone that has done thousands of oil changes in south Florida on generators , mowers, and small engines, you see patterns. What works, what doesn’t. You see guys using 30 weight oil (their request) with low hours on their engines and the engines are starting to prematurely smoke.
If you live in arctic conditions , or have an oil cooler , or water cooled, then 30 weight is acceptable.
In Houston or Florida in a generator? You really can’t go wrong with a 40 weight to START.
If I owned a Honda 2800 watt generator in Houston , it would get SAE40, 15W40, 5W40, etc. changed every 50 hours.