What is Dexos, and what do the numbers 0W20 represent?

The dexos® specification is uniquely designed to complement the exacting requirements of GM’s advanced engine technology. The specification has gone through an extensive developmental and testing process.  It requires a number of proprietary tests that are not included in current industry standards and sets performance criteria at a level that exceeds many current standards.  The result is a high performance fluid providing significant wear protection, improved piston cleanliness, a reduction in volatility and oil consumption, enhanced aeration control for improved fuel efficiency and better oxidation properties.

0W20 represents the standard of measure SAE; measurement of oil viscosity. Viscosity is a measurement of the oil’s resistance to flow. The more resistant the oil is to flow, the higher its viscosity. An optimal viscosity for oil is based on engine load and speed conditions. Ideally, the goal is to balance low-viscosity oil that provides little resistance to motion — saving fuel and efficiently transferring power — with high-viscosity oil that protects the contact area between metal surfaces.