Oil Additive FAQ

  • What do STP® Oil Treatment products do?

    • Motor oils are carefully formulated lubricants that perform many important functions including cooling engine parts, keeping them clean and protecting them against wear. One of the most important functions of oil is to lubricate by forming a cushion between moving parts to help them slide easier. 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 thicker cushion of oil between moving engine parts, thus helping to protect against engine wear.

  • Should I use STP® Oil Treatment products before or after an oil change?

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

  • Why does STP® make two different oil treatments? What are their differences?

    • There are two separate and distinct STP® Oil Treatment products:

    • STP® Oil Treatment (in the blue bottle) helps protect against engine wear with a high-viscosity formula, which fights metal-to-metal friction, by providing a thicker cushion of oil between moving engine parts. It can be used in all cars, trucks and SUVs.

    • STP® Oil Treatment (in the silver bottle) contains a seal swell and also helps protect against engine wear by increasing oil viscosity, which provides a thicker cushion of oil between moving engine parts and reduces metal-to-metal friction. It counteracts oil thinning and also contains zinc additives to boost motor oil’s anti-wear protection. It helps stop engine leaks, noise and smoking that can be more common in higher mileage vehicles.

  • Where does sludge come from?

    • 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 the 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 pick-up 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, preventing it from accumulating inside your engine.

  • Do STP® oil additives cause sludge?

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

  • How often should I use STP® Oil Treatment products?

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

  • How much will the STP® Oil Treatment products treat?

    • The 400 mL STP® Oil Treatment product is designed to be mixed with 4 to 5 liters of motor oil.
  • Why do some car manufacturers recommend against the use of oil additives in my car?

    • 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.
  • Do you have an oil treatment for winter?

    • STP® does not manufacture an oil treatment specifically for winter use. STP® Oil Treatment and STP® Multipurpose Motor Treatment can be used year-round.

  • Are STP® oil additive products safe for two-cycle engines?

    • The STP® Multipurpose Motor Treatment can be used in two-cycle engines.

  • Are STP® oil additive products safe for four-cycle engines?

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