Hello everyone , I started using Briggs & Stratton fuel fit stabiliser last year as a effort against E10 , it protects against ethanol and one thing it claims is to keep petrol usable for up to 3 years !!!. So I’ve done a little test, last October I half filled my 10hp Briggs generator with E10 and added the required amount of fuel fit , I’ve been starting it every month since and this weekend is a year the same petrols been in and it’s still starting good !, I know it’s not been 3 years but to keep the petrol usable for 1 year will do for me !!. The down side is it’s only available in small bottles. I hope this might help if your not sure which additive to try