#Define viscosity in oil code

However, for other oils, such as those containing polymeric viscosity index (VI) improvers, or heavily contaminated or degraded fluids, this relationship does not hold true, and can lead to errors if we are not aware of the differences between absolute and kinematic viscosity.įor a more detailed discussion on absolute versus kinematic viscosity, refer to the article “ Understanding Absolute and Kinematic Viscosity” by Drew Troyer. However, it is the oil’s resistance to flow and shear due to internal friction that is being measured in this example, so it is more correct to say that the gear oil has a higher absolute viscosity than the turbine oil because more force is required to stir the gear oil.įor Newtonian fluids, absolute and kinematic viscosity are related by the oil’s specific gravity. The force required to stir the gear oil will be greater than the force required to stir the turbine oil.īased on this observation, it might be tempting to say that the gear oil requires more force to stir because it has a higher viscosity than the turbine oil. Use the rod to stir the oil, and then measure the force required to stir each oil at the same rate. To measure absolute viscosity, insert a metal rod into the same two beakers. Which one will flow faster from the beaker if it is tipped on its side? The turbine oil will flow faster because the relative flow rates are governed by the oil’s kinematic viscosity. Imagine filling a beaker with turbine oil and another with a thick gear oil.

#Define viscosity in oil code

Whereas the higher the second part of the code (number), the better it is for higher temperatures.An oil’s kinematic viscosity is defined as its resistance to flow and shear due to gravity. The first part of the numerical code (5W) tells you the lower the number, the better it will perform in low temperatures. It is represented by a number followed by the letter ‘W’ (WINTER) and a number again. The SAE (Society of Automotive Engineers) have a standard for indicating low and high viscosity engine oils for the right temperature. At low temperatures, synthetic oils flow easily and maintain viscosity at high temperatures. But synthetic oils are able to do the same without the incorporation of additives. Conventional mineral oils are mixed with various additives to help change the viscosity index.

These viscosity changes are related to engine-protection and efficient-operation in all conditions.Ī lubricant’s resistance to thinning at higher temperatures is known as viscosity index. A higher viscosity lubricant will be less fluid and thicker in nature whereas oils with low viscosity are thinner and flow freely.

The oil becomes thin at high temperatures and thick at low temperatures. They lubricate the engine responsibly and accordingly, hence considered more dependable.Įngine oils are affected by changes in temperatures. At high temperatures, multigrade oils oppose thinning out and in colder conditions, they remain fluid. They show oils that have two viscosity grades are since, indicated the same as monograde oils are but adding another number. They flow smoothly without thinning out and are most useable for present-day vehicles. These contain the best of both worlds and are not affected by both low and high temperature. For eg SAE International engine oils 8, 12, 16, 20 and so on. High engine viscosity grades use only numbers to indicate and are most suited to higher temperatures. These are more fit for engine-use in colder temperatures. According to SAE International standards, they are 0W, 5W, 10W, and so on. The symbol of low engine viscosity grades is with a ‘W’ at the end. These engine oils are more suited to low temperatures and cater more to older vehicles. Based on the types of viscosity grades or standards, We can differentiate them into monograde and multigrade oils. This will avoid wear and tear in the engine parts and act as a layer of protection. As the lubricants will be thicker and highly viscous, the flow of the oil through the engine will be slower. On the contrary, engine oils with a high viscosity grade are best in hotter temperatures. This helps in preventing a cold engine start in chillier conditions. It will not be thinning out and have better fluidity because the oil has low viscosity. Engine oils have viscosity grades to show the engine oil’s adapting to varying high and low temperatures.įor example, a low engine oil viscosity will perform better in colder temperatures. The viscosity grade of an engine tells you how smoothly or easily the oil flows in your engine at different temperatures.