What Are API Motor Oil Ratings?

When shopping for motor oil, you may have noticed that most motor oil bottles come with an API rating. Let’s talk about what an API rating is and how it can help you find the best motor oil for your vehicle.

What Is An API Rating?

There’s an organization called the American Petroleum Institute. Their purpose is to thoroughly evaluate every blend of motor oil before it hits the market. The oil manufacturer will have developed the blend for a specific rating. API will determine if the oil meets their criteria for the rating. If it does, the manufacturer is allowed to put the API rating on the label.

The Standards The American Petroleum Institute Uses

American petrol institute

The organization borrows its standards from the International Lubricant Standardization and Approval Committee (ILSAC). The committee is spearheaded by U.S. and Japanese automobile manufacturers. ILSAC has quite high standards. For instance:

  • The motor oil must meet stringent requirements for:
    • Phosphorus content
    • Low temperature operation
    • High temperature deposits
    • Foam control
  • The motor oil must contribute to:
    • Improved fuel economy
    • Improved volatility
    • Deposit control
    • Reduced oil consumption rates
  • The motor oil must provide enough viscosity over its service life
  • The motor oil must contain additives that won’t degrade over its service life
  • The motor oil must:
    • Provide high temperature deposit protection for pistons and turbochargers
    • Be compatible with the emission control system
    • Be compatible with all the seals within the engine
    • Provide protection for engines operating on ethanol-containing fuels up to E85

The American Petroleum Institute evaluates each blend of motor oil to see if it meets all the standards set above. If the blend passes all the tests, then it gets a seal of approval on the label with an API rating.

It’s a good idea to always use motor oil with the correct API rating. That way, you’ll be sure that the motor oil will provide the protection and viscosity your engine needs. The one-size-fits-all approach doesn’t work with motor oil. There are many different blends of motor oil. Some blends work better with older engines. Some blends work better with newer engines. Some blends are only for diesel engines. Some blends are only for gasoline engines. You get the idea.

Finding The Right API Rated Motor Oil For Your Application

API ratings

Shopping for motor oil involves reading labels. The trick is to know what to look for. First, you want to find motor oil that’s suited to the fuel you use: gasoline or diesel. There’s an easy way to find out.

  • An API rating that starts with the letter “S” indicates that the oil is for gasoline engines
  • An API rating that starts with the letter “C” means that the oil is for diesel engines

Next, find the right API rating for your vehicle. The newer your vehicle, the more important it is to use the most current API rated oil. It’s because the most current API rated motor oil blends are formulated for the most modern engines. Motor oil evolves alongside engines. More modern engines need oil with:

  • Better viscosity
  • Better protection
  • Better compatibility with the new and improved parts

If you have an older engine, it can’t hurt to use the most current API rated oil. The opposite isn’t true, though. If you have a newer engine, you can only use the most current API rated oil. If you use older API rated oil, the oil may not meet your engine’s demands. This guide has a list of the most current API ratings.

Do you have any questions about API motor oil ratings? You can contact us. We’ll be happy to answer your questions.