Now that you know what motor oil does for your engine, the next step is to make sure that you know what goes into picking the right type of oil. While there are numerous varieties of oil on the market, there are four basic things to keep in mind when choosing the right oil for you car. While your manufacturer’s guide is the best place to learn the best type of oil for your vehicle, these basics will help you understand just what exactly you are putting into your engine.

API Symbol
The first thing to look out for when buying motor oil is the API symbol. API stands for the American Petroleum Institute, which is responsible for giving different ratings to the various types of motor oil. The API uses two symbols to display their ratings, the API “donut” and the API Certification “Starburst.” The donut, which is divided into three parts, shows the oil’s performance level, its viscosity, and its energy conserving potential. The starburst symbol means that the motor oil has passed the tests for meeting the minimum industry requirements.

Viscosity
Viscosity is a test developed by the Society of Automotive Engineers (SAE) that indicates how well the oil flows at specific degrees. The two temperatures are 0 degrees Fahrenheit (-17.8 degrees Celsius), and 212 degrees Fahrenheit (100 degrees Celsius). Viscosity is designated by an number, such as 5W-20 or 10W-30. The two numbers means that the oil has been tested at both temperatures.

Quality
 There are several different types of oil, including conventional, semi-synthetic, full synthetic, and high mileage. Different vehicles will require different types of oil based on the type of engine and its performance needs.

Additives

The last thing to look out for when buying motor oil is the type of additive packages that are included in the oil. Most manufacturers add an assortment of minerals and chemicals to the oil. These additives fundamentally change how the oil works within the engine. Additives are specifically designed to make the oil work better within a specific type of engine, such as an engine with high-mileage or one that is aging. It is best to know the particular state of your engine before you buy motor oil with any particular additives.