i agree with the other posters, use Stabil, i used it for a 7 months trip and it was all good, also i would unhook the battery for the extended trip and possibly put it on stands to get the tires off the ground and they wont get flat spots.

What I would do though since you are going to be gone for 2 years, is sell it to a friend with the clause of buying it back when you return, but that is just me.