What is the viscosity index?

The viscosity index (VI) is a scale used to measure how the viscosity of oil or flow resistance changes depending on its temperature. Generally speaking, the less it changes, the better. The scale of the viscosity index has the nature of the numeric, with zero is the most susceptible to changes in viscosity. It is a common foundation for comparison in the automotive industry and is often shortened as VI. As it decreases, friction and heat increase, which can lead to mechanical failures. The longer the oil can maintain its optimal viscosity, the more efficient the engine to make the engine and prevent damage. In this way, the viscosity index may be a useful way to assess the total oil quality and this is the necessary information when choosing oil for cumbersome use involving wide temperature changes.

The oil viscosity index is based on the I.TS measured viscosity at 100 ° F (40 ° C) and 210 ° F (100 ° C), which closer to the temperatures present in the engine when it is first turned on, and then after warming up. The smaller the change, the higher theScores on the index. Oil technology has improved from the development of the viscosity index as a comparative tool and grew up the original scale, which only took place at 100.

Best Modern Synthetic-TJ. Oils created by a person can evaluate more than 400 on a scale, while oil based on oil can exceed 100 brands. For easy comparison, the scale is sometimes divided into several wide categories, while the oils scored below 35 classified as "Low VI;" Those who scored between 35 and 80 as “medium vi;” Oils between 80 and 110 rated "High VI;" and those above 110 classified as "very high VI."

However, there are disadvantages of the high viscosity index. To achieve very high scores VI, oil manufacturers usually injure the ingredients specially designed to withstand the effects of temperature change. There is a limit of how many of these ingredients can be added without affecting another desired featureI oils.

It is even more important that the ingredients tend to burn under pressure. This can leave oil unable to withstand thinning and eventually unable to protect the engine at high temperatures. As a result, the viscosity index should not be when the oil should use, even if it remains a very useful piece of data.