Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/778560
48 | January - February 2017 | www.machinerylubrication.com BACK PAGE BASICS With motorcycles and the broad range of temperatures in which they are driven, you will need an oil that can provide protec- tion at colder and startup temperatures but also offer protection once the engine is hot. This can be achieved with a multigrade oil. For my first motorcycle, the manufac - turer suggested using an SAE 10W30 oil. The "SAE 10W" signifies that the oil will act as a 10W grade at colder temperatures. The "W" stands for winter. Having a lighter viscosity fluid is crucial on startup so that all internal components are lubricated quickly, reducing the amount of wear. The "30" in the designation is a measure of the oil's viscosity at 100 degrees C (212 degrees F). This indicates how thick the oil will be at the engine's operating temperatures. Motorcycle-specific Oils vs. Automotive Oils One of the main differences between a motorcycle engine and an automobile engine is that motorcycles typically use a combined sump for the transmission and engine. Automobile oil formulations gener- ally have special friction modifiers blended in to increase fuel mileage and decrease wear. In a wet sump application, these fric- tion modifiers would interfere with clutch performance. I've heard the argument that motorcycles have higher engine tempera- tures and speeds, but I don't believe this plays a major factor in oil selection. Instead, a motorcycle oil should be chosen for the intended application or at least meet all the service designations. In 1998, JASO introduced a rating system for motorcycle oils. Previously, the majority of motorcycle oils utilized auto- motive oils as a base. As automobile manufacturers began requiring more fric- tion modifiers be used in their vehicles, these formulations caused clutch slippage and gearbox pitting. JASO specified four grades: JASO MA, MA1, MA2 and MB. The first three (with the designation of MA) signif y that the oil is intended for a four-stroke motorcycle with an oil sump for the engine, gearbox and clutch. MA fluid is non-friction modified. If an oil is rated at MA, it means the oil's test results were between MA1 and MA2 standards. JASO MB grade oil is also designed for four-stroke motorcycles but has lower friction properties. These oils are not to be used where a ser vice designation of MA is required. Synthetic vs. Mineral When choosing between synthetic and mineral oils, you must understand what makes the two different. Mineral or conventional oils are refined from crude oil and separated into API classifications of Group I, II and III. The higher the classi- fication, the more refined the oil. Due to the refining process involved with Group III mineral-based oils, lubricant manufac- turers can legally market these oils as synthetic even though they do not have a true synthetic base oil. Synthetic oils hold an API classification of either Group IV or V. Synthetics are man-made fluids with uniform oil mole- cules. Their viscosity generally remains more consistent across a broader operating range, which means they are ideal in colder conditions and high heat applications. An oil's change in viscosity with respect to a change in temperature is known as its viscosity index (VI). The higher the viscosity index, the less change in viscosity of the oil. Synthetic base oils are known to have viscosity indexes of 150 and higher. Multigrade mineral oils are formulated with viscosity index improvers. While this makes the oil useful over a broader oper- ating range, it can also have drawbacks, such as with the shearing of the viscosity index improver. At higher temperatures, these viscosity index improvers shear down faster and allow the oil to degrade quicker. For instance, an oil that began its life as an SAE 10W40 could break down to an SAE 10W30 or thinner. Synthetic base stocks have few if any viscosity index improvers but are still able to achieve multigrade requirements. Lubri- cant manufacturers blend in more performance and longevity additives to make the oil last longer, decrease wear and provide better mileage. The improved mileage and horsepower come from the oil molecules being uniform and in reducing the amount of fluid friction within the lubricant film. Selecting the Right Oil In conclusion, it's best to choose a viscosity range based on where and how you ride. For me, the perfect selection is an SAE 10W40 synthetic, as I like to get in a few last-minute rides before storing the bike for winter but also need protection for when temperatures reach 100 to 110 degrees F during summer. People who ride in Texas may require added protection on the upper end of the scale but not so much on the lower side. For those who ride up north in places like Wisconsin, an oil with a good cold range should be considered. I don't discourage anyone from using a conventional oil in their motorcycle. The choice is completely yours. For me, I prefer the comfort of knowing that I can get a little longer out of an oil change. In the end, always try to select an oil that's right for you and your bike. About the Author Garrett Bapp is a technical consultant with Noria Corporation, focusing on machinery lubrication and maintenance in support of Noria's Lubrication Program Development (LPD). He is a certified lubrication specialist through the Society of Tribologists and Lubri - cation Engineers (STLE) and holds a Machine Lubrication Technician (MLT) Level II certifica- tion through the International Council for Machinery Lubrication (ICML). Contact Garrett at gbapp@noria.com. 56% of lubrication professionals do not know what to look for when selecting a motorcycle oil, according to a recent survey at MachineryLubrication.com