When two surfaces rub against each other, friction will occur. Friction generates heat and thus a loss in power with wear and tear deforming or destroying the two materials. Introducing a lubricant between the two surfaces has the effect of reducing the friction causing the damage. Optimal lubrication is achieved when the exact film of oil is between the two surfaces.

As an oil moves / runs it meets with resistance, described as viscosity. As the viscosity level increases as temperature decreases, and vice-versa, the flow is altered.

The viscosity index applies to the viscosities of the oil at various temperatures – at the higher index of the lubricant the more stable the viscosity of the oil at temperature and under load.

The Society of Automotive Engineers’ international classification of oils on the basis of their viscosities. Grades marked ‘W’ are at a temperature below 0oC (W = winter). The lower the number next to the ‘W’, the lower the pouring temperature of the lubricant.

Mono-grade oils, as by their name, work at their optimal lubrication at a limited outside temperature range. Multi-grade oils have a stretched range of viscosity which allows a greater difference of outside temperature for optimal lubrication.

This is the lubricants capacity to remove / clean the varnish and carbon residues deposited inside the engine

This is the oil’s capacity to prevent the accumulation and deposit of sludge.