What Does The “W” Stand For In Oil (Such As 5W-30)

18. What Does The W Stand For In Oil1
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I’d like to discuss a few connected subjects in this blog. First, I want to answer what “W” stands for in oil type. Then, I’d like to discuss their classification and efficacy.

When engine oil is labeled 10W30, it means that the viscosity is rated at 10W when the engine is cold and 30 when the engine is hot. This is distinct from oil with a 5W30 designation, which has a thinner viscosity when the engine is cold.

Short Answer: W Stands for Winter

“W” stands for “winter.” Oil grades that contain a hyphen (i.e. 10W-30), this indicates range of viscosity attainable with this particular oil, namely it behaves like 10 weight oil (less viscous) when it is cold or “winter” and thanks to viscosity modifiers (manufacturer added oil additives), it will behave like 30 weight oil (more viscous) when hot.

Long Answer:

Single-grade Oil

In keeping with the discussion from the brief answer above, SAE, or the Society of Automotive Engineers, has successfully implemented the motor oil grading system that we all use. The confusion of using “weight” all started from For single-grade oil, refer to SAE J300 designation guidelines. Single-grade oil is frequently used in industrial settings with little variation in temperature or in specialized applications like air compressors, lawnmowers, and some classic cars. The 11 single-grade oil types that are available are 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50, and 60, in accordance with the definition provided by SAE J300. All the numerical values are correctly referred to as “weight” or “straight-weight” oils. It is correct to say 20 weight oil for 20; 5W should be referred to as 5 weight winter-grade oil. Yes, that W remains “winter” no matter what.

18. What Does The W Stand For In Oil2

Multi-grade Oil

So what makes single-grade and multi-grade oil different from one another? When the application, like cars, did not require a wide range of temperatures, single-grade oil performed admirably. Extreme temperature changes will occur in an automobile’s engine. If you start your car in Kodiak, Alaska, you might find that the motor oil is inside the engine at -30F. Due to the thermostat and combustion heating, the engine may reach a temperature of 180F when you drive to the store. The oil also warms up at this time. An increase of 210F has occurred! As you can see, if a single-grade oil was used in this application that was only meant to operate at -30F, the engine would probably seize or suffer harmful wear at 210F, and vice versa, assuming no Polytron MTC oil additive had been used.

In order to run your engine as efficiently as possible, multi-grade motor oil simply transforms its viscosity based on the operating temperature. When you’re cold, you want things that are low viscosity (flow easily, like water), and when you’re hot, you want things that are high viscosity (flow difficult, like honey). Such skills are a result of specialized polymer additives called Viscosity Index Improvers (VIIs), which are added at the motor oil manufacturer. Observe that viscosity varies logarithmically with temperature for different grades, meaning that viscosity changes ten times more than temperature changes. I’ll end here because this is starting to get a little long. Oh, and some more enjoyable things!

Fun facts:

  • Without VIIs, multi-grade oil can be produced. If this occurs, it may be sold as either single-grade extremes, such as 20W-20 without VII, or 20 weight single-grade.
  • Gear and axle oils do NOT have the same grade as motor oils do! Higher number oils, like 75W-140, do not imply they are more viscous than motor oil because SAE J306 defines the gear oil grades differently, and they are measured on different scales.
  • One of the most popular motor oils, 10W-30, is already mixed into Polytron MTC to mix effectively with your primary oil. Additionally, we manufacture Polytron-infused Full- and Semi-Synthetic Motor Oil.

Importance of a Viscosity Scale

The Society of Automotive Engineers (SAE) created a viscosity scale so that there would be a uniform method of determining the viscosity of engine oil. The thickness of the oil is measured on a scale from 0W, which is the thinnest type, to 60, which is the thickest type.

The “W” that you see on oil labels stands for the word “Winter” because this portion of the label shows the viscosity level of oil when an engine is cold.

Thicker motor oil can flow more rapidly and easily. This is crucial because the oil needs to quickly lubricate the machinery when you start a cold engine. It can do that because of low viscosity motor oil. On the other hand, you don’t want your motor oil to be too thin when the engine is hot. Because the oil is thicker and has a higher viscosity, all the engine parts are kept well-lubricated and separate.

How 10W30 Oil Affects Equipment

Although understanding oil viscosity is crucial for effective fleet maintenance, it also has an impact on a variety of industrial equipment’s performance. Viscosity, for instance, can affect how much heat is produced by cylinders and bearings. Viscosity can also have an impact on how quickly oil is used up and how simple it is to start and run equipment in extremely hot conditions.

You will use less oil and experience less wear and tear on your vehicles or equipment if the oil has a higher viscosity or is thicker at warm temperatures. However, a thinner viscosity oil can aid in improving an item of equipment’s start-up and lowering fuel consumption.

There may be sporadic contact between machine parts due to improper oil viscosity. If this is left unchecked, your equipment will begin to deteriorate and have issues. As a result, it’s critical to include routine oil changes in your preventive maintenance program in addition to choosing the appropriate type of oil for each application.


What Do the Numbers on Oil Mean

You might be familiar with terms such as “30-weight” or “10W-30” oil. Those numbers represent the grade. The oil is thicker the higher the number. The lower the number, the thinner.

What Does 5w-40 Oil Mean

“5W” stands for flowability at cold temperatures (It is still pumpable at -35 °C, or liquid enough to reach all lubrication points in the engine at low temperatures. The second part, “40”, describes the flowability of the engine oil at an operating temperature of 100 °C.

What Does the Second Number in Oil Mean

The second number refers to viscosity at normal engine operating temperatures. Some examples: the “5” in a 5W-30 motor oil will protect an engine down to an air temperature of about -25 degrees Fahrenheit.

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