one of the guys on the car fix fourm said any cleaner that has b12 in it. i think he mentioned chemtrol with b12 these guys are either working techs at various dealerships or retired techs and that question went around last week
if you have an adapter to connect to the fuel rail before teh high pressure pump you might try just pumping the tank dry and then refilling with 5 gallons to get you back teh a station, that pumps the bad gas into a gas can that may just work in the mowers. i had that this spring i got bad gas in the s10 and it had misfires up the ass and so i connected up to the fuel rail and let the fp pump out the gas until it stioped pumping and then pt in 5 gallons from a different station and all was good.
i do not know about where you live but gas has injector cleaner in it by law around here, also as we get the additive for water in the gas as well. in michigan anyway. good luck