Various Properties of Lubricant

Viscosity: The property of lubricant which is a measurement of the internal friction of lubricating oil is called its viscosity. The viscosity of an oil is specified in time (seconds) taken by the given quantity of oil to flow freely through a standard size hole at given temperature.

Viscosity Index: Every lubricant thins out when its temperature increases and gets heavier as temperature decreases but this change does not occur at the same rate for every lubricant. A number is given to indicate the rate at which it thins out or gets heavier; this is known as viscosity index.

API Classification: American Petroleum Institute (API) gives a classification for various oils as per the ingredients in the oil. Some of the functions of these ingredients are : anti-foaming, anti-septic, anti-rust, etc.

The classification starts from

SA, SB, SC, . . . , SJ . . . etc.

SAE Number: SAE viscosity numbers are recommended by Society of Automotive Engineers (SAE). The range of viscosities within which it falls at the given temperature determines the SAE viscosity number of any lubricating oil. The lubricating oil recommended by Hero Honda Motors Ltd for their 100 cc models is of grade range SAE 20 W 40 SJ and for 125 cc is SAE 10 W 30 SJ grade.

The lubricating oils of the following SAE grade range are generally available in market.