There are many types of engine oil, but it's fairly easy to determine what kind you should use in your car. Your owner's manual should tell you the appropriate viscosity of oil — like 5W-30, for instance — that your engine requires, and the viscosity may also be stamped on the oil reservoir cap on the engine itself. Viscosity is the measure of how much resistance a fluid has to flowing. Many would refer to it as the "thickness" of a fluid; honey has more viscosity than water, for example.
There's more to oil, though, than just viscosity. The American Petroleum Institute certifies oil based on performance criteria determined by automakers, engine builders and oil producers. Oils that meet the standards receive the API Certification Mark, which should be easy to see on an oil container.
There's more to oil, though, than just viscosity. The American Petroleum Institute certifies oil based on performance criteria determined by automakers, engine builders and oil producers. Oils that meet the standards receive the API Certification Mark, which should be easy to see on an oil container.