Gumout Multi-System Tune-Up is recommended for use in all types of engines. Other Gumout fuel additives may be used at the recommended dilution rate in the gasoline. For example, the 6 oz Regane Complete Fuel System Cleaner treats 21 gallons. To five gallons, use 1.5 oz – or ¼ of the bottle. The rest may be saved for later use or added to a car or truck fuel tank to treat about 15 gallons.