Rec fuel has a 2 year shelf life, I have been using it for the past 14 years with SEAFOAM and never had a problem. Mix 1 or 1 1/2 oz. with every gallon of gas, take boat and trailer for a ride to mix and you should be fine. When storing for the winter fill tank/seafaom, don't run carbs try, turn key off put batteries on maintenance charger and fog engine. You'll be fine till spring.