What Fleet Owners Need to Know About Oil Grades

Oil grade is determined by the viscosity property of the oil. Viscosity refers to the ability of a substance to flow. For motor oil, this means testing its ability to flow through the engine at certain temperatures. Oil grades are important for fleet owners because it directly affects the durability and fuel efficiency of your engines. For example, a high viscosity indicates the oil is thicker and is ideal for warmer temperatures. In contrast, a thin oil can still flow easily in colder temperatures. There are also multi-grade oils such as SAE 5W and 10W-30 that can perform at both high and low temperatures. These multi-viscosity oils are great for trucks that may be traveling long distances from one climate to another. For more about oil viscosity and how grades are determined see oil viscosity.

How oil viscosity effects fuel economy

Large diesel engines need to be able to withstand heavy loads and wear and tear. They need high viscosity oils to ensure durability for the long haul, however as regulations of emissions begin to tighten, trucks also need lubricants with minimal amount of Sulphur by-product. The downside to these thick oils is the amount of energy the engine uses to pump this oil, which uses up fuel. Chevron has been testing lower viscosity oils on multiple engine types in various environments and has found that you can see fuel efficiency increase with no loss in performance by switching from a 15W-40 to a 10W-30 oil. With diesel prices on the rise considering the fuel economy of your fleet is becoming more important. For more information about these tests see Chevron’s Key Considerations for Shifting to a Lower Viscosity Oil.

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