Engine-Oil Glossary

September 28, 2010

If you haven't already heard or read about CI-4 engine oil, the industry's newest lube for use in four-stroke-cycle diesels, be assured that CI-4 will be part of your life if you operate and maintain diesel-powered trucks or equipment. To help you better understand CI-4 information you may hear or read, here's a quick glossary of terms you may encounter.

  • Additives... Chemical substances added to petroleum products to impart improved properties.
  • Ash... The residue of metal-containing detergent additives when oil is burned in the combustion process.
  • Base Stock... The fluid, either refined from crude oil or created by combining different chemicals, into which additives are blended to produce finished lubricants. Base stocks are classed into five groups.
  • Detergent... A metal-containing additive (commonly calcium, magnesium or barium) generally considered as the oil's primary acid-neutralizing agent.
  • Dispersant... A non-metallic additive that helps prevent sludge and varnish by keeping insoluble particles suspended.
  • Synthetic Oil... Oils with base stocks produced either by highly refining (and altering the molecular structure of) petroleum, or by chemically reacting various compounds. Base stocks for these oils may be Group-3 petroleum products, chemically engineered Group-4 fluids or a blend of either with Group-1 or Group-2 base stocks.
  • TAN... Total Acid Number is the quantity of base compounds, expressed in equivalent milligrams of potassium hydroxide, that is required to neutralize all acidic constituents present in one gram of engine oil.
  • TBN... Total Base Number is the quantity of perchloric acid, expressed in terms of the equivalent number of milligrams of potassium hydroxide, that is required to neutralize all base-compound constituents present in one gram of engine oil.
  • Viscosity Index... Measure of a fluid's change in viscosity (resistance to flow) with temperature. The higher the viscosity index, the smaller the change in viscosity with temperature.