are chemical substance added to a petroleum product to impart or improve certain properties. Common petroleum product additives are: anti-foam agent, anti-icing additive, anti-wear additive, corrosion inhibitor, demulsifier, detergent, dispersant, emulsifier, EP additive, fluidizer, oiliness agent, oxidation inhibitor, pour point depressant, rust inhibitor, tackiness agent, viscosity index (V.I.) improver.