What Motor Oil Numbers Mean and What it Does for Your Vehicle

October 18th, 2012 by
Oil Change

Learn about motor oil numbers at Cox Mazda.

So, you’ve decided to take the plunge and try to change the oil for yourself. When you look at the selection at the automotive store, though, there’s a myriad of different options, each labeled with a cryptic series of numbers and letters. You’re sure that somewhere among the different choices, there’s the silver stag, the oil that will make your engine run perfectly, while a wrong choice will inevitably lead to a catastrophic, full engine meltdown that takes your sanity with it.

The latter isn’t necessarily true, but it’s good to use the oil recommended by your manufacturer to avoid engine problems. In your vehicle manual, your manufacturer will list what type of motor oil to use, and oftentimes some alternatives. If you’re still unsure, you can always ask your local mechanic. Some people are just happy stopping at knowing what type to use, while others would rather understand more about the intricacies of motor oil. Many of the tips in this guide come from an informative blog from Cox Mazda.

Motor oil works as a lubricant for the different moving parts of in your engine. Your engine goes through some drastic temperature changes, from freezing cold in the winter to burning hot when it’s running. Temperature naturally affects the viscosity of your oil, making it thicker in cold temperatures and thinner in warm. Too thick and the oil can’t move and get to the places it needs to, and too thin, it doesn’t lubricate well.

Motor oil is labeled with a series of numbers with a dash in the middle. The lower the number before the dash, the better the oil is at flowing when it’s cold out. A ‘W’ right after this number stands for ‘winter.’ The number after the dash is a rating of how the oil performs in warmer temperatures. It’s important to follow you manufacturer’s specification because not all engines are equal; each is designed to handle different viscosities.

When buying oil, look for the “doughnut” and “starburst” badges on the bottle. These are designation set up by the American Petroleum Institute, or API. Choosing oil with these badges tells you that you’re getting a quality, certified brand.