Low Temperature Viscosity Requirements for Engine Oils in Temperate and Tropical Climates

Some 30% of the world's car population spread over a large proportion of the world's land mass rarely experiences starting temperatures lower than 0°C (32°F) , but frequently encounters high temperatures in the order of 40-50°C (approx. 100-120°F). The present SAE ‘W’ classification, as applied to multi-grade oils, more than satisfies starting requirements in these climates but imposes unnecessary expense and limitations on the nations concerned.

A proposal is made to extend the existing SAE classification by defining an SAE 30W number for use in temperate and tropical climates.

Data generated from testing of representative oils in glassware and commercial engines are presented.