STP® Diesel Treatment is designed to help reduce fuel consumption and emissions by keeping the fuel intake system clean of harmful deposits and reducing emissions and smoke. STP® Diesel Treatment contains cetane improver to facilitate starting in winter. STP® Diesel Injector Cleaner has been specially formulated to help restore performance and efficiency by dissolving harmful deposits. It also smoothes out rough idling and helps reduce fuel consumption and tailpipe emissions. In most cases, the difference is noticeable within 80 km.