• Motor oils are carefully formulated lubricants that perform many important functions, including cooling engine parts, keeping them clean, and protecting them against rust, corrosion, and wear. One of the most important functions of oil is providing lubrication by forming a cushion between moving parts to help them slide more easily. This reduces metal-to-metal contact and friction — a major contributor to heat, wear, and premature aging of engine parts. STP® Oil Treatment fights this metal-to-metal friction by providing a thick cushion of oil between moving engine parts, thus helping to protect against engine wear.

  • STP® Oil Treatment can be added at any time. For maximum results, it’s best when added to fresh oil in a warm engine right after an oil change.

  • Sludge is a thick, sticky residue that can form inside your engine through a combination of combustion by-products (oil oxidation residue, carbon and water). Water condenses as a result of a hot engine cooling down. The oil mixes with the resulting water and forms a thick sludge that sticks to the engine parts. Frequent cold starts and short trips contribute to this condition by not allowing the engine oil to heat up enough to vaporize and remove the water. Sludge is detrimental in that it can clog key oil passages such as oil drain-back holes and, in some cases, block the oil pickup screen in the oil pan, causing engine oil starvation (i.e., not enough oil). STP® Oil Additive products contain detergents, which can help suspend sludge in the motor oil and prevent it from accumulating inside your engine.

  • No. STP® oil additives contain detergents, which can help suspend sludge in the motor oil and prevent it from accumulating inside your engine.

  • STP® Oil Treatment products can be added at any time and are best added at every oil change. They should, however, only be used once per oil change and according to package instructions.

  • See packaging or product page for treat rate.

  • Many car manufacturers state that after-market oil additives are not necessary, even though they sell their own brand of oil additives. Some after-market oil additives contain corrosive chemicals, including chlorine-based lubricating compounds that may be harmful to internal engine parts. STP® products do not contain any corrosive components and are safe for use in all engines.

  • The STP® oil additive products have not been tested and are not recommended for use in two-cycle engines.

  • The STP® oil additive products are specifically designed for use in four-cycle engines.