Choosing Viscosity Grade

The most known engine oil viscosity classifications are as follows:

SAE (Society of Automotive Engineers) Classification:

The SAE classifications characterizes the viscosity at low and high temperature of the lubricant. The grade is given by two numbers separated by the letter W (meaning winter).

The first number, followed by W represents the low temperature viscosity, 5W, 10W, 15W... the lower this number, the more fluid at low temperature the oils, the easier the engine starts.

The second number gives the high temperature viscosity: 30, 40, 50. The higher this number, the more viscous the oil when hot.