How long is it ok for my vehicle to sit without starting?

You can leave Your car sit without starting for up to a year or more with proper preparation. The first thing You're going to want to do is change all the fluids and oils just to make sure there in tip top shape. Is storing for up to a year, top off the gas tank to prevent condensation inside of it and add a fuel stabilizer. If storing for longer than that drain the tank completely because the fuel will go bad. Connect a trickle charger onto the battery so that will maintain we charge. It would be good to place the car on jack stands to prevent the tires from getting flat spots. Cover any intake openings to prevent mice and other critters from crawling and building a nest inside the engine. Placing mothballs around the vehicle can deter some pests.