Looking at getting a gallon of Stabil 360 marine to use mainly in cars, maybe some small engines, looks like you get 4x the gallons of fuel protection for $15 more than the regular Stabil, seems very worth it. But if I don't finish it in 2 years will it be completely useless? And is there even any real proof anywhere that it's worth adding this to cars that sit for months? I see everyone talking about it vs regular and others but I never see any real evidence.