Opti-Lube Summer+ Formula Diesel Fuel Additive: Quart Treats up to 640 Gallons Boosts Cetane and Enhanced Lubricity for Reduced Fuel System Wear. Improved Fuel Economy, Increased Power Cleans Injectors, reduceses Deposits and Emissions. Prevents Rust & Corrosion Improved Water Separation and Storage Stability (More than doubles storage life of diesel fuel) Improved Storage Stability (More than doubles storage life of diesel fuel)