A tip from the Sprint Car community...Use Marvel Mystery
Oil. It mixes well with gasoline to burn /flush out when you re-fire the engine. It will leave no residue or foul the spark plugs. WD40 will leave a waxie residue and does not clean out as well when you re-fire the engine
Pull the injectors, Squirt them with some in the fuel rail connection and the nozzel then re-install them. Spray some down any metal line and seal the line with a bag, tape plug, etc. I suggest that you pull the block coolant drains on the engine and leave them out. Also pull the rocker arms and spark plugs, squirt some marvel into the cylanders and rotate the engine over at least once to coat the cylander walls. Re-install the spark plugs and
leave the rockers out. This will prevent corrosion/rust in the cylanders and keep the valve springs from getting weak. You can put some in the gas tank, slosh it around, then put it in a plastic bag.
You also should seal up all breathers, etc. that will let any moisture/allow condensation to protect the engine internals.
Change your engine
oil just before you re-fire the engine the first time. This will flush out any marvel that has weeped past the rings and drain out any condensation (water) from the engine.
I have used this process for storing/winterizing engines for many years
If you can't find any marvel you can use Automatic Transmission Fluid (non-
synthetic) instead but you will want to clean it out of the fuel system with some carburator or brake cleaner before fireing the engine.