Why was Group II+ base oil developed?
Chevron produced the first Group II+ base oil commercially in 1998. It is the most cost effective base oil for 5W-20 and 5W-30 passenger car engine oils of GF-3 quality. Group II+ has higher VI, which translates to improved (low-temperature) cold cranking performance and lower volatility. The cold cranking performance of a 5W-XX engine oil is measured at -30°C using a Cold Crank Simulator, and the volatility of the engine oil is measured using the Noack Test, which simulates oil evaporation in an engine-like environment.
