I didnt empty it prior, I dumped two bottles in, and ran the dog snot out of it to empty the tank. When I put the truck into storage now for deployment, I dump a couple bottles of Stabil in it, and fill the tank to the brim. When I get back from deployment (like I did last year) I dumped two bottles of Seafoam (yeah probably overkill) then immediately ran the tank almost dry. Its the same thing I do to the oil, minus the heet. Prior to my last deployment, I did a complete oil change, then when I pulled it into the storage lot, I pulled the fuel pump relay, and the feeds going to the coil, and used Deep Creep engine fogger and had my bud spin the engine over a couple times while I sprayed the snot out of the intake to fog the cylinder walls. When I got back, I hooked everything back up, and it smoked like a pig for bout five minutes as it burnt the fogging oil off the cylinder walls. Oh- if you put the truck into storage, and there is air space in the tank, that is a place where condensation can build up. Fill it up fully before you turn it off for storage..