What is Viscosity?

Understanding Motor Oil

You get it that there are different kinds of motor oil–conventional, full synthetic, synthetic blend, and high mileage. But then there are various viscosities. What is that? What should you choose? Visit Jeff’s Auto Repair on Sandpoint Way, Seattle, Washington, for expert advice from our ASE certified technicians. We can help you select what’s best for your car or truck based on climate conditions, your driving habits, the age of your car, and the manufacturer’s recommendations.

Understanding Viscosity

When you pour motor oil, it acts differently according to its viscosity, the measure of how well oil pours at a certain temperature. Thinner oil has a lower viscosity, and it pours more easily in cold temperatures than does higher viscosity, thicker oil. Which is better? It depends on the conditions and uses. Lower viscosity engine oil works well to reduce friction between engine parts. It also acts a bit quicker when your car starts in cold weather. Higher viscosity oil, on the other hand, is good at creating and maintaining a sufficient film over engine parts. Also, the thicker oil is more effective at sustaining oil pressure when hauling heavy loads. To understand what you’re buying, look for the Society of Automotive Engineers (SAE) scale. The initial digit (in front of the “W”) is the viscosity. It indicates how well the oil pours at certain degrees of temperature. Lower numbers thicken less in cold weather. The “W” stands for winter. The two numbers after the “W” give the viscosity at 100 degrees Celsius, showing you how well the oil resists thinning when exposed to heat. Oils with lower numbers thin out quicker than do higher-numbered oils.

Thinking About Viscosity

As you think about the viscosity of engine oil you want to buy, check the manufacturer’s recommendation as listed in your owner’s manual. Also, think about the driving conditions where you live. If most of your driving occurs in cold temperatures, a lower winter viscosity motor oil might be an appropriate choice for you. Conversely, you may select a higher viscosity oil if most of your travels are in hotter conditions. Our expert staff at the Sandpoint Way location of Jeff’s Auto Repair in Seattle, Washington, can assist you with the best choice of motor oil for your vehicle as well as all your car service and repair needs.