The Star brite 93664 Star-Tron Fuel Tank Cleaner is a concentrated gas/diesel formula in a 64 oz size. This enzyme-based additive disperses sludge and fuel contaminants from gasoline and diesel tanks, offering a cost-effective alternative to professional cleaning. To use, add 1 fluid ounce for every 4 gallons of gas or diesel fuel and allow it to sit in the tank for a minimum of 24 hours before using the fuel.