Most of us are familiar with seeing the term SAE, most commonly when looking at or purchasing engine oil, or getting the oil changed on your vehicle. But what is SAE and why is it important?
SAE stands for Society of Automotive Engineers. The organization was founded in 1905, with the mission of creating a place where designers of early automobiles could come together and collaborate to improve the automobile product offerings, by making them safer, more reliable and more cost effective to consumers. Early founders and officers in the Society of Automotive Engineers included famous people such as Henry Ford and Orville Wright.
The organization grew rapidly, and more and more people in the automotive industry saw merit to having a place where ideas and technical information could be exchanged freely within the industry, as it made improvements in automobiles happen faster. Thus the impetus for having an organization that helped automobile manufacturers coordinate and share information was born. Eventually, SAE grew to include engineers and designers from other sectors of the transportation industry, such as tractors and airplanes. Today, they have over 100,000 members from all segments of the mobility and transportation industries.
What does all that have to do with oil? It become clear at some point, that a large part of the value of having an organization from across the entire industry, was that they could use the breadth of influence to coordinate standards for various parts of the industry. One of the places that desperately could use some standardization was in engine oil. There are many different types of standards for automotive oil, but the SAE is primarily concerned with standardizing how the thickness, or viscosity, of oil was measured.
The benefit to having viscosity measurement standardized is that now consumers, technicians and manufacturers had a better way to ensure the oil they were using in a car would be sufficient in lubricating the critical wear surfaces in the engine, and not cause premature failure by either being too thick or too thin. Viscosity, as just mentioned, is the relative thickness, or ability of oil to flow. The SAE has a panel of engineers that determines how to measure and standardize relative viscosity of oils. The standards for measuring viscosity are set for in SAE’s J300 document, which goes over what the different weights and tests used to measure the relative viscosity of an oil.
There are two temperature ranges where viscosity is measured, at operating temperature and at cold temperature. There are some oils that have one viscosity whether cold or warm, and these are called single-grade oils. They are not very common today. Most all motor oil used now is multi-grade, meaning it was one viscosity when cold and another when warmed up. The SAE uses a cold engine cranking simulator to measure how thick or thin the oil is when cold. It then tests using for high temperature shear properties using a tapered bearing simulator, which gives an indication of how thick or thin the oil is at operating temperature. Both of these tests are critical to ensure that a multi-grade oil will offer the necessary protection in whatever engine application it is being used in.
It is also important to note that the SAE oil viscosity standards have nothing to do with the quality of the oil. There are many ranges of quality in oil, in any given viscosity range. The SAE standards around viscosity are simply there to codify and standardize how oil thickness is measured. The SAE plays an important role in helping to set standards throughout many different aspects of the automotive and other transportation related industries. Having many of the basic aspects of these industries, like how we measure thickness of oil, standardized helps keep our cars, trucks and other trusted machinery running smoothly.