Improves oil performance. Extra protection for vehicles over 75,000 miles. Rejuvenates seals and gaskets. Helps stop engine leaks, noise & smoking. Contains zinc anti-wear agent ZDDP. Suitable for all seasons. Scientifically engineered for high-mileage vehicles using conventional or synthetic oils. Seal Swell Agent: Helps stop engine leaks, noise and smoking; helps reduce oil consumption. High-Quality Base Stock: Carrier of active ingredients to help protect internal engine parts. Viscosity Index Improver (VII): Cushions engine parts to help reduce metal-to-metal contact. Zinc Dialkyl Dithiophosphate (ZDDP): Anti-wear agent that helps provide a layer of protection for engine parts. 100% satisfaction guaranteed or your money back. www.stp.com. Questions? 1-888-G04-STP1 in the U.S.A. Made in USA for Energizer Auto.