Post your engine model xxxxxx, type xxxx, trim xx, code xxxxxxx numbers. Are you using 93 octane gas with fuel treatment to take care of ethanol problem ? What brand of fuel treatment? Stay away from Stabil fuel treatment.
I disagree with you. I use 93 octane gasoline in everything from pickup truck to outdoor power equipment. I use 5w-30 full synthetic oil in my Vanguard engine per instructions in Operators Manual. I suggest you carefully read your engine manual. Vanguard Big Blocks use 15w-50 full synthetic per recommendations in Engine Manuals. I also use B&S OEM parts for my Simplicity lawn tractor.