Originally Posted by wag123
Small air cooled lawnmower engines have such a low compression ratio that they will run good on 81 octane gas, if you could buy it.
87 octane gas will work fine. Higher octane than this would be a waste of money, but E0 would be preferable to E10 if it is readily available in your area..
My old briggs flathead recommended 77 octane or better. But my chonda wants 87, per manuals.
I ran my briggs on "white gas" when gas was $4/gallon-- I got the can at a yard sale. It ran fine, exhaust smelled funny, but if I put more gas than I needed in it would evaporate out over the following week!