What's in engine oil?
While the vast majority of engine oil is, of course, crude oil, there are a few things added to make the oil suitable for your car. You'll also find things like detergents, which clean the spaces between moving parts and nooks and crannies where grime and old oil can build up, anti-wear (AW) additives that prevent certain materials from wearing out sooner, dispersants that prevent oil and other waste materials from clumping together, and viscosity improvers that help the oil to flow better, especially when it's cold.