STP Synthetic Oil Treatment provides extra protection for extended oil drain intervals that come with synthetic oil use. Re-formulated for use with low-viscosity oils, this engine treatment offers the same benefits as traditional STP Oil Treatment. ZDDP oil additive helps to protect against engine wear to keep your car running efficiently. These engine oil additives use detergents to prevent engine deposits so your engine runs clean, and antioxidants help to enhance oil durability by reducing oil breakdown and preventing oil burning. Add this treatment during every oil change to protect your engine without diluting your motor oil.