I am Firefighter /EMT in my town we have multiple Gas and Gas oil mix tools on average we were sending out tools every 2-3 months for carburetor repairs cleaning and adjustments, one solution we tried was running the tools 15 min every week, still resulted in engine problems. I know in the lawn care business you guys are running the tools a 100 times more than that. There is nothing worse than trying to start a saw to vent a roof or trying to fire up a pump engine to operate a hydraulic tool and not being able to get it to run, or walking into the station and having fuel running out of the compartment because the fuel line rotted away.
On the recommendation of a Stihl dealer we switched to SEF94 fuel. It is a small engine racing fuel (Not cheap about $8-14 a gallon). Since we made the switch after the initial run in period and minor adjustments the tools start right up and have no issues we are actually back to running the tools 1 time per month as opposed to 5 times. Other agencies have switched to Tool fuel and True fuel, and seem to have had similar results (I have been using True Fuel in my personal equipment found it at Lowes). Iím not sure if any of you have tried these fuels but there is no ethanol in them and you can even buy it in premixed cans for your different tools. The cost may be a preventive factor for some running it in mowers, but for trimmers and chain saws it might save money in the long run. Since I didn't see any posts on these alternates to gas station fuels I thought I would throw it out there for consideration.