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What difference does viscosity make to oil?

Ensuring that engines and machines are well lubricated is vital to how well they work, and with so many different types of oils on the market, it is important to make sure that you are selecting the right one for your particular device.

When selecting lubricants, you should always pay attention to the fluid’s viscosity, as this is one of its most important characteristics. The term ‘viscosity’ describes how thick the lubricant is, and is measured by the ‘weight’ of the oil. Thicker lubricants tend to have a higher viscosity.

This can be both advantageous and a hindrance, as they can last longer, but in cooler temperatures, may take longer to reach the engine. Oil’s viscosity can decrease with increasing temperatures, meaning that it becomes thinner, but it will thicken when the temperature goes down.

Viscosity in cars

Motor oils are becoming thinner, especially multigrade lubricants that are labelled in a manner such as ‘10w-40’ and ‘20w-50’.

Multigrade oils change their viscosity with the temperature. If taking ‘10w-40’ as an example, it will behave like a 10-winter lubricant when cold (the lower the number, the quicker it will get to work in low temperatures) and a 40-winter oil when hot.

Having this type of lubricant in the engine will help to perform, no matter the weather. Manufacturers normally recommend the optimum oil viscosity for their products, but higher viscosity lubricants can be used if you anticipate operating in extreme temperatures.

Different characteristics

Not all oil responds in the same way to a temperature fluctuation, as some have the ability to resist such viscosity changes. This is referred to as the VI (Viscosity Index). On this scale, the higher the VI, the less the oil’s viscosity will be altered by a temperature change.

Selecting the right oil, with the right viscosity, is an important piece of the puzzle when ensuring that your engine is lubricated enough to perform to the desired level.

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