What Does 'S' Stand For On Engine Oil Packaging?

For any vehicle, the most important factor in prolonging its usability and preserving its performance is regular maintenance and servicing. For vehicle maintenance, oil changes are essential because of the critical function that motor oil serves. When choosing which oil to use, it is important to check the vehicle manual and the information found on the oil container.

Motor oil containers or packaging normally have labels that show the API (American Petroleum Institute) specifications of the oil. Among the many numbers and letters indicated as the product category is the letter S, a classification meant to show that the oil is used for spark or service ignition engines.

A spark or service ignition engine is the most common type of internal combustion engine and is normally fueled by gasoline. As the name indicates, a spark engine uses a spark plug to ignite the fuel-air mixture in the cylinders. Engine oils that have the S designation are formulated specifically for gasoline engines and have lower viscosity to help with lubrication and fuel efficiency and contain fewer additives.

As the largest trade association for the United States oil and natural gas industry, the American Petroleum Institute works with the public and private sectors to influence public policy and regulations related to the oil and natural gas industry. It also develops and publishes industry standards, including those for petroleum and oil products.

Engine oil products that have the API category and ratings, including the S on their containers, have undergone the voluntary Engine Oil Licensing and Certification System – EOLCS from the API. This licensing and certification program means that companies and brands that have met the specific requirements of the API can use the API Engine Oil Quality Marks in their products.

The API standard for gasoline engine oils is a continuously evolving service category, and new standards for oils are then created and applied as technological development for both diesel and gasoline engines moves forward. The very first was API SA, which applies to gasoline engines made before 1930/ New standards have been added throughout the years, with its naming convention done by simply adding another letter in alphabetical order for each new standard. Currently, the newest S standard is the SP standard, which was introduced in 2020.

Car manufacturers have varying recommendations for changing motor oil. Generally, it is between 5,000 and 10,000 kilometers, but this also depends on driving conditions, accumulated mileage, and engine type. What is important to consider is that motor oil will degrade whether the vehicle is being used or not, and it will need to be replaced eventually.

With a wide selection of engine oils available in the market, the option of which oil to use should be based not just on its advertised specifications but also on how it would impact the long-term maintenance of the vehicle. This is because the costs incurred with each oil change will add up over its lifespan, and the sensible alternative could be a balance of price and features for whatever product is to be used.

From a larger perspective, API standards serve an important role in the American oil and natural gas industry by driving continuous improvements in safety, product quality, and environmental compliance. However, its more practical and perhaps more impactful benefit is that it provides vital information about engine oil products to the public and gives some guarantee of the quality of products that millions of consumers regularly buy.