3. SAE classification

This universally applicable viscosity classification takes into account various cold and hot viscosity criteria. Dating back to 1911, it is regularly updated to keep pace with engine requirements in terms of cold-operability and hot-safety.

The late 1999 version (SAE J300 DEC99), in force in 2003, defines eleven viscosity grades (table 1 ).

• Winter" grades

There are six of them, labelled "W" (from the English abbreviation "Winter"), and they are characterized by two viscosities measured at low temperature.

The first is cold-start viscosity. It is measured on a rotating dynamic viscometer called the "Cold Cranking Simulator" (CCS) (figure