I have started a regimen with my small engine gasoline I buy; I use the blue marine Sta-Bil at 1oz/gallon which helps with phase separation, and I use 1oz per gallon seafoam motor tune. I do this to my big 5gal can, from this I will fill a 1-gallon can for my weedeater and ice auger and add oil for 20:1 ratio. I leave fuel in all of my engines when not in use and have had zero diaphragm or varnish problems. Ethanol blended fuels tend to varnish easier it seems, the seafoam keeps that from happening, and the sta-Bil keeps the ethanol from settling out from the gasoline if saturated with moisture.

I quit using 92/93 octane gas in my small engines as well. The muffler on my snowblower would glow red on high test gas. It doesn't do it on regular 87 octane. Rumor had it that the slow burning gas is still burning when getting blown out the exhaust valve and the muffler glows because of that. I just figured small engines run better on non-ethanol gas... At least for me, they don't.