For example, 5W-30. The numbers indicate the thickness ... For instance, the oil cap on my Range Rover says, "Castrol ...
Castrol 5W-30 F-Trucks CK-4 has been designed to meet Ford Trucks’ WSS-M2C213-A1 specification, which is based on the Association of European Automobile Manufacturers’ (ACEA) Oil Sequences E6 and E9 ...