current thinking on storage regarding fuel systems is that it is probably best to at least drain the tank to 1\4 to keep the fuel off of the pump boot. In my opinion it is best if you drain the tank. that way the hose to the pump doesn't sit in the fuel either. Here in n.j. the fuel has up to 10% mtbe additive yearlong as an oxidizer to reduce pollution. not only is it a known carcinegen it contaminates groundwater and breaks down rubber.Every day in this metro area you hear about another car fire. when you consider the effect of mtbe on the rubber components of your fuel system and the fact it is under high pressure; about 75 psi a minor leak will destroy the car quickly.besides it is a good time to inspect a hidden area of the car and remove any dirt.