What, do you have a Ferrari lawnmower?
A Briggs and Stratton was designed to run on kerosene or gasoline, I've run my snowblower with up to 50% diesel. So the alcohol is no problem.
You just don't want to leave any gasahol in the tank when you're done. Run it dry.
Even if I run it dry it runs like crap it eventually fubar’s your carb, I don’t want it period.