Finding the Right Oil for Your Car in Winter

Ever wander down the aisle in the store with the wall of car oil? There are so many numbers and letters on the packages, it can leave you wondering why you were there in the first place. With all the choices for oil, it’s important you know what type of oil works best for your car. At Siskiyou Import Services, we want our drivers to know about what goes into their cars, especially in the cold winters of Ashland, Oregon. Here is a list of the most important things you need to know about your car oil, including classification codes, viscosity, and oil additives.


Understand the Codes


A bottle of oil will have two circular stamps on the label. One has a starburst edge, and this symbol means the oil passes SL service tests for engine protection and fuel economy. The other symbol, shaped like a doughnut, is the API stamp, and it tells you that the oil meets the current SL service rating for the engine type it goes in (gasoline or diesel). You will find the Society of Automotive Engineers (SAE) viscosity number in the center.




This refers to the ability of oil to flow through your engine. A lower number on the stamp indicates thinner oil, which flows easily. You can purchase one of two types of oil: single-viscosity and multi-viscosity. When you see 10W-30 on a bottle of oil, for example, you are looking at multi-viscosity oil. The first number indicates how well the oil flows in cold temperatures and the second one shows how it does in hot temperatures.


Viscosity Index


This index demonstrates an oil’s resistance to thinning, which it does when heated. The higher the second number on that oil rating, the better it resists thinning. Oil that can’t resist thinning won’t last as long. Oil faces a lot of abuse in your engine, particularly from shearing, where close-fitting metal surfaces slide around (e.g., bearings, pistons, etc.) on surfaces. Resistance to viscosity loss in such places is critical to your engine’s performance and protection.


Different oils exist to provide the kind of performance and protection cars need in a variety of circumstances. To get your car’s oil changed, contact Siskiyou Import of Ashland to schedule an appointment. While you’re there, feel free to ask our technicians any other questions you may have about oil and what’s best for your car.


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