6495 College Park Dr, The Woodlands, TX 77384

Understanding Oil Grades and Why It Matters to Your Car

Understanding Oil Grades and Why It Matters to Your Car | Repair One in The Woodlands, TX. Image of a male customer having difficulty choosing engine oil in the car supermarket.

Regular oil changes are an essential part of vehicle maintenance. But there’s trouble in scheduling an oil change without the awareness of oil grades and viscosity. This leaves drivers on the verge of using unsuitable oils.

However, you’ll never experience this issue when you visit Repair One. As your local automotive experts in The Woodlands, TX, we will always perform oil changes with the correct oil. And we’re also here to help you understand the various oil designations. 

Let’s take a closer look at engine oil grade and viscosity and why they matter. If you need a professional oil change, don’t hesitate to contact Repair One in The Woodlands, TX.

Oil Viscosity and Oil Grades

Viscosity (sometimes known as flow rate) refers to how thick the oil flows through an engine. A lower-viscosity oil is thinner, meaning it will flow easier than a more viscous oil. 

If you were to look at an engine oil container, you’d notice it carries a number. This is the SAE number (named after the Society of Automotive Engineers, which came up with the grading scale). It lets you know the viscosity of the car oil. 

Since engine designers build their engines with a particular viscosity in mind, an SAE grade lets you know if you’re using the right oil for your engine.

Multi-grade vs. Single-Grade Oils 

SAE numbers for multi-grade oils are in the format of “XW-XX.” The “X” and “XX” stand for two numbers: 

  • The first number tells you how thick the oil is at a temperature of 0°F. 
  • The second tells you how thick the oil is when it reaches 212°F (the typical operating temperature of a modern engine).


These numbers help determine if the engine oil viscosity is thin enough when you start your engine in cold conditions. If it’s not, your engine might seize while warming up. Moreover, the “W” in the SAE number means the oil is graded for winter use. 

Let’s take 5W-30, a multi-grade oil, as an example: 

  • “W” means it’s graded for winter. 
  • The first number (5) is the viscosity at 0°F. The second number (30) is the viscosity at 212°F. 
  • The lower viscosity at lower temperatures means this oil won’t be as thick at normal temperatures. This is the reason 5W-30 is recommended for cold temperatures. 


There are also single-grade oils, like SAE 10, 20, 30, 40, or 50. They only have viscosity specified at 212°F. With no flexible flow rates, don’t expect these oils to protect your engine in cold conditions.

Contact Repair One to Learn About Oil Grades in The Woodlands, TX

When choosing the best oil for your vehicle, it’s imperative to get it right. The best place to get this information is your owner’s manual. If you don’t have it or aren’t sure of your car’s requirements, don’t worry. Your helpful technicians at Repair One in The Woodlands, TX can help. 

Call us today at (936) 271-1110 or complete this online form. Also, feel free to stop by our shop at 6495 College Park Drive, The Woodlands, TX 77384.

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