The meaning of viscosity and oil viscosity

Document Type:Research Paper

Subject Area:Engineering

Document 1

The meaning of viscosity and oil viscosity? To understand viscosity you should imagine how different liquid flow in the pipe. For example, honey flows faster than water in a pipe. Which mean water has low viscosity but honey has high viscosity. Viscosity is the physical property of the liquid. By that viscosity is a measure of a fluid resistance to flow and shear. Late model vehicles usually have a preference for the high-mileage oil as it is formulated to that kind of vehicles. The high mileage motor oil usually has some unique additives of the used formula that usually aids in the burn–off of oil, and also helps in the prevention of leaks that may occur in the engines that are older, (Nesbit 54).

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There are a number of viscosity grades and the conventional motor oils can also be formulated into this, and the quality levels are usually very different. The drivers with simple car engines are usually advised to use conventional motor oil more often. What is the number 5W-30 mean in oil engine container? Looking at 5W-30, we got two sets of numbers 5W and 30. The reason behind the oil is tested at 100C because that considered a working temperature for the average engine. Which is the best grade oil for use in my motor? Put that question to a group of “knowledgeable” motorheads and the fur will fly. Pronouncements of doom and direct consequences will abound, usually supported by half-truths, urban myths, and anecdotal experiences giving rise to a general atmosphere of fear, uncertainty, and doubt (FUD).

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A good understanding of the information presented above will help dispel much of that FUD and aid you in making a well-informed choice. In general, you are best served to simply follow the recommendations of the engine manufacturer, (Farndon 32). For more detailed data on a specific oil, you need the oil manufacturer’s data sheets, (Farndon 32). These data sheets are readily available from most manufacturer’s websites and contain some of the actual SAE test results for that specific product. Let’s consider a common situation as an example and see how it might be analyzed. What do the SAE numbers on a container of motor oil mean? SAE J300 Motor Oil Specification (ca. 1911) SAE Grade Flow Rate @100° C 10 <= 14 seconds 20 15 to 24 seconds 30 25 to 34 seconds 40 35 to 44 seconds 50 >= 45 seconds To properly answer that question a bit of history is required.

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A major change was made in 1952 when the original set of grade designations was augmented with the addition of a set of winter (“W”) grade designations (10W, 15W, 20W, 25W, 30W) which were specified by viscosity measured at 0° F. This change was instituted to address problems with cold weather oil performance. Engineers and consumers alike had come to realize that the existing grade specification did not adequately describe the cold weather nature of existing motor oils. At freezing temperatures, an oil meeting specification SAE 20 refined from aromatic black Gulf crude was much thicker than an SAE 20 refined from light amber Pennsylvania crude. Engineers began to measure this difference in behavior with a viscosity ratio metric called the Viscosity Index (VI).  Oil.

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