Decoding Motor Oil Labels

Decoding Motor Oil Labels

Choosing the right motor oil for your vehicle is important to its longevity, and is as easy as looking in your owner’s manual for the recommended type. But have you ever wondered what all of the symbols, letters, and numbers mean on a bottle of motor oil? Wonder no more! We have decoded them for you:

First things first: the starburst symbol is the API (American Petroleum Institute) certification mark and indicates that the oil meets the most current requirements of the Lubricant Standardization and Approval Committee(ILSAC)’s minimum performance standard, very important. You should definitely choose an oil with this symbol on it.

Then to the right of the starburst symbol is a donut symbol that contains three pieces of information:

1. The top half of the donut describes the oil’s performance level. For a gasoline engine, look for the letter “S” for “Service.” Oil for diesel engines has a “C” for “Commercial.” The letter that follows the “S” is what you need to check your owner’s manual about. The letter recommended for your engine will depend on how old it is.

2. The bottom half of the donut indicates whether the oil has demonstrated energy-conserving properties.

3. The center of the donut contains the SAE (Society of Automotive Engineers) viscosity number. Motor oil thins as it heats up and thickens as it cools, so the label has a number for both high and low temperatures. The first number stands for how viscous the oil is at 0 degrees Fahrenheit, which is why it is followed by “W” for “Winter.” The second number represents how viscous the oil is at 212F.

In cold temperatures, motor oil has to be resistant to thickening so that it flows more easily to the engine parts. Excessive thickness can make it harder to start the engine, which reduces fuel economy. The lower the first number, the more easily the engine will start in cold weather. The more resistant the oil is it is to thinning, the higher the second number. Thicker oil generally seals better and maintains a better film of lubrication between moving parts. Check your owner’s manual for the viscosity grade that is suitable for the temperature range you will be operating your vehicle in.,

Now that we have helped you decipher the cryptic meaning of the symbols on your motor oil. Any questions? Let us know in the comments section below.

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  1. […] also important that you use the right motor oil for your vehicle.  Check out our past blog post, Decoding Motor Oil Labels, to learn […]

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