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What’s The Weight of Oil? What Does the ‘W’ in Oil Grades stands for?

Oil is one of the primary ingredients for any operating machine or engine. You may have seen labels such as 10W-30 and wondered what the mysterious “W” might stand for in connection with oil labeling. Because a majority of lubricant manufacturers use such form of labeling, you are not alone in asking this question. There are a number of other curious users out there who want to know the answer to this question. Read on to find out what it actually stands for and why it is an important element of oil labeling.

• What Does the ‘W’ in Oil Grades stands for?
Interestingly, there are two versions of answers to this question: long and short. Labeling consists of a range with an upper limit and lower limit. The ‘W’ here stands for winter.
In the label 10W-30, 10W indicates that the oil shows lesser viscosity resembling SAE 10 oil when its temperature is low in winter. On the other hand, 30 indicate the viscosity of the oil when its temperature is high and sometimes it is called oil weight .
Each lubricant company uses this form of labeling to enable it’s buyers to find out the viscosity characteristic or behavior of its oil.
As far as the category of oils is concerned, two forms of grading are widely accepted in the industry at the present time: single-grade oil and multi-grade oil.
SAE, the acronym for Society of Automotive Engineers, is the association which is responsible for the viscosity designation of rules for oil grading.

• Single-grade oils
Single-grade oil refers to the kind of oil which does not operate at a wide range of temperatures summer and in winter. That is to say, this type of lubricants does not adjust to temperature variations. In a majority of cases, single-grade oil is used for a wide range of industrial purposes. SAE 50 CH4 is an example of a single grade diesel engine oil.

• Multi-grade oils
Multi-grade oil, as the name suggests, refers to oil that can operate at various temperatures. This type of oil is mainly used in the automotive industry and in a few industrial applications like in gear oils. SAE 15W-40 CH4 is an example of a multi-grade grade diesel engine oil.

• Why is it that multi-grade oils are exclusively used in motor engines and not for industrial purposes?

The answer is simple. In most industrial tasks, the temperature variation is not necessary. This is because industrial appliances generally operate at a constant or fixed temperature. Even as there is a variation of temperature, it is negligible in terms of its effect on the oil.

However, it is a different thing altogether when it comes to using oil for the engines of automobiles. Multi-grade oil is made to adjust to the temperature fluctuations automatically. In other words, its viscosity decreases when the weather is cold and vice-versa. Viscosity Index Improvers (VIIs) – a special type of additives – help multi-grade oils to make an adjustment with varying temperatures. This is necessary to keep a vehicle up and running. In the event the vehicle oil fails to attain viscosity in line with the atmospheric temperature, it comes to a grinding halt.

Now that you know the significance of “W” in connection with grading by lubricant suppliers, make a point of studying oil grading in detail for gaining an understanding of it. We hope this article was helpful for you to understand what actually ‘W’ means in the labeling of oil.

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