Liquid Amoxicillin prescription bottle. Very leak proof, and it holds exactly enough for adding one gallon at a gas station. The DS rides I do are all less than 100 miles, and my 3.4 gallon IMS tank plus one extra gallon is plenty for the day.
Make a man a fire, and he'll be warm for one night. Set a man on fire, and he'll be warm for the rest of his life.