Engine oil. It’s the unsung hero of the internal combustion engine. Your vehicle’s engine contains hundreds of moving parts with very fine clearances between them. Lacking a protective layer of oil to lubricate everything can lead to grinding, overheating, and even total engine failure! Even the best designed, most efficient engines would grind to a catastrophic halt without a few quarts of the golden good stuff circulating around and keeping everything moving smoothly.
Despite performing the same duty, all engine oils are not created equal. In this article we’ll look briefly at the ways in which oils can differ and then we’ll answer the question that the title asks: between 0W40 and 5W40, which is best?