As I do every 5000 miles, I put a full bottle of Red Line SI-1 into the 20 gallon tank of my Ranger. Usually I use that tank of fuel in about a week, but this time it will sit. We're going on vacation, and the majority of this fuel/Red Line mixture will be sitting in the tank for about 2 weeks. How caustic is the SI-1, will it harm anything by just sitting, or will it just clean the tank better? Thanks for any help!