Re: lifespan of engines
Oh you should get more 5000 miles, If you take decent care of it. They are rough, but in some ways that means they will keep on going. Respond to the odd noise, change the plug, watch your chain or bag the nasty chain altogether.
Yes a good synthetic oil will help…..but even 20:1 seems really strong. You could go 30:1 easy with something like Saber.