The Process Behind API's Engine Oil Certification

Aug. 1, 2019

From collection to the testing facility, follow the certification process that leads to the industry standard in quality control.

They are the ubiquitous “donut” and “Starburst” labels on most major motor oil containers.

The labels depict an American Petroleum Institute (API) service category and certification that remain voluntary but are mainstream in the industry.

API has issued standards since 1947, when it decided to identify different additive qualities in addition to the SAE viscosity classifications already in use. API has updated its standards 10 times since. Industry groups work with API on the details of those standards. 

The latest current category is SN (including SN Plus), but some older service categories are still in use for gasoline engines today. In June, API announced that certification for the newest service category, SP, will begin in 2020.

The organization has certified products for those specifications for 35 years, says Kevin Ferrick, API director of product programs.

“In the North American market, nearly every oil marketing company is licensing their product through API,” he says.

The Engine Oil Licensing and Certification System is how a motor oil company gets to use those certification labels. API charges fees for use of the labels, and it also oversees the tests of products to make sure the product meets the standards depicted.

The labels are so big in the industry that some packagers have added them without any actual certification. Most are familiar with it, but are you familiar with what work goes into getting that approval?


In most cases, API will simply buy motor oil off the shelf to test brands. But API also collects bulk tank samples from quick lubes and other related facilities.

Ferrick says that roughly one-third of the samples come from bulk tanks. 

“If they’re buying bulk, the collector has a gallon jug that they go to an oil change location,” he says. “They do identify themselves as working on API’s behalf.”

From there, the samples are shipped to Texas.

Motor oil samples are sent to laboratories that specialize in lubricant properties. A 10W-30 has to meet those viscosity properties at high and low temperatures. If a 10W-30 sample doesn’t meet those properties, it could be pulled from shelves or even recalled.

It also helps operators be sure that they’re getting what they pay for.

“They want to make sure that the right viscosity, the right product, is going into their tanks,” Ferrick says.

One of those testing entities is Southwest Research Institute in San Antonio. The labs’ work covers an array of research and development areas, including biomedical, aerospace and environmental.

Southwest’s work in the automotive arena includes lubricants testing. There’s a whole menu of tests for the motor oil properties. Viscosity is one of the simpler tests to do, and that’s done to make sure the sample matches the SAE grade.

There are tests to measure an oil’s performance in higher temperature parts of the engine. There are tests for different driving conditions, all to see how the oil and the engine parts hold up.

“A big part of engine oil is protection of the seals and gaskets,” says Michael Lochte, a director of the Fuels and Lubricants Research Division at Southwest. “And so there is a series of elastomer compatibility tests that are run on the oil to make sure that it protects.”

Elastomers are substances like rubber and others with similar qualities.

To measure oil properties, the best way to conduct a test is to fire up a brand new engine, which is what Southwest does to test for oxidation. The engine is run really hot for a long time.

“Run for 90 hours,” Lochte says. “And the engine is taken apart at the end. It is rated for piston deposits. It could be carbon and varnish that could be on the pistons.”

Industry Changes

Fuel economy is a big arena for motor oil testing at Southwest. Engines are run with a sample oil at different loads to simulate various driving conditions.

Lower viscosity oils are becoming more common to help efficiency, and thus, they’re being tested more often, Lochte says.

Manufacturers developed direct-injection engines to help meet efficiency standards. Those designs had issues like low-speed pre-ignition (LSPI).

Motor oil formulation has emerged as a way to combat LSPI, or “super-knock.” Motor oil standards like API SN Plus were developed as designations for this very issue. Thus, Southwest tests oils for those standards.

Southwest takes an engine—in this case, a Ford four-cylinder—and tests for the conditions that produce LSPI.

“There are pressure transducers that are installed to measure the pressure inside the combustion chamber,” Lochte says.

The engine is run to simulate a heavy load. Lochte says that the exhaust manifold glows red. The measurements should be able to register any premature ignitions that create LSPI, and Lochte says the tests create massive amounts of data in real time.

To meet the latest standards, Lochte says that an engine with the sample oil must have no more than five LSPI events per 170,000 engine cycles.

“It’s amazing the amount of R and D and testing that goes into a quart of oil that you can buy for just a few dollars,” Lochte says.

Product Placement

While the labs do the testing, it’s ultimately up to each operator to make sure they’re giving customers the right product as advertised.

One way to ensure that is pushing for complete, detailed labeling and receipts—from the distributor to the customer. That was one topic covered in an education session at iFLEX in May. Presenters from the Automotive Oil Change Association talked about their work to promote best practices.

A large part of this push is to be sure that shops are compliant with labeling regulations, because a failed inspection can disrupt business. But another part of that is helping to make sure that the product being sold has the exact specifications on the label. And if the product is something different, there’s a paper trail to find out what happened.

“Most consumers and especially distributors hadn’t been used to seeing these things from us,” says Victory Lane CEO Justin Cialella at iFLEX. “The good operators, I think, have always been transparent about this. Now it’s going to be much more of a standard and much more of a requirement going forward.”

Ferrick with API also suggested that operators get as much information as they can about the products they get from distributors. Accidentally mixing multiple products could have unintended consequences.

“We’ve seen situations where there was co-mingling of two different oils into a bulk tank, and unfortunately it throws off the test results,” he says.

The entire process is meant to ensure that operators, as well as customers, get what they pay for.

API Testing By The Numbers

In 2017:

1,300 samples collected
343 of those were from bulk tanks
Variety of viscosity grades used
Largest share are the traditional 5w20, 5w30 and 10w30
30 percent of samples from quick lubes
1 percent from truck stop/travel centers
31 percent from repair shop/garages
36 percent from dealerships
2 percent from other facilities