I concur with Jeffh and the "fog" process is not needed. In New England, i've winterized three yanmars, 2QM, 3QM, & the 4 series (only the 2QM was raw water cooled). Never have i removed the fule injector during winterizing.
I'm hessitant to add any thing to the fuel system, but the fuel. And engine block drain, i assume you mean change the oil? That, i'd do, but repalce/refill the oil.