Global environmental and regulatory trends aimed at reducing emissions are compelling automakers to improve fuel efficiency and lower emissions from passenger cars and light-duty trucks.

These developments require new types of engine oils capable of better protecting modern, compact, and highly precision-engineered engine components. As a result, a new category of gasoline engine oils—API SQ—was introduced in 2025.

The American Petroleum Institute (API) is the leading industry association and standards-setting authority in the petroleum sector. Its lubricant standards are developed through a rigorous accreditation process covering performance, safety, reliability, and environmental impact. First presented at the API Lubricants Group meeting in June 2024, API SQ builds upon and significantly enhances the performance and protective capabilities of the previous API SP standard.

Bill O’Ryan on API SQ

““API has been diligently working with ILSAC and industry stakeholders to develop new oils to meet the needs of the current and future engine technologies to comply with upcoming regulations” said Bill O’Ryan, Senior Manager of API’s Engine Oil Licensing and Certification System (EOLCS/DEF).

Juri Sudheimer on API SQ

SCT Lubricants, under the leadership of Juri Sudheimer, exemplifies how leading lubricant manufacturers are adapting to these new requirements.

“API SQ is not just another name or a race for letters in a specification. We began adapting our formulations long before the official launch of the standard because we clearly saw where engine technology was heading: downsizing, higher loads, sensitivity to LSPI, and timing chain durability. Our objective is to produce oils that are ready for these new demands under real-world operating conditions. That is why MANNOL and SCT products developed with API SQ requirements in mind are the result of engineering solutions and extensive laboratory testing aimed at achieving maximum performance,” Juri Sudheimer shared.

Performance Requirements of the API SQ Standard

Gasoline engine technologies are rapidly evolving toward more compact and highly efficient designs that meet increasingly stringent fuel economy and emissions requirements. This trend is commonly referred to as downsizing.

Every automaker seeks to extract as much horsepower as possible from each liter of engine displacement. Without debating the pros and cons of this modern engineering approach, it is important to note that today’s engines place fundamentally different demands on engine oils than previous generations.

Engine oils formulated to meet the API SQ standard are designed to address several key challenges, including:

Improved Fuel Economy

Engine friction is a primary source of energy loss. Enhanced anti-friction properties in engine oils help reduce internal resistance and improve overall fuel efficiency.

Protection Against Low-Speed Pre-Ignition (LSPI)

LSPI (Low-Speed Pre-Ignition) is the premature self-ignition of the air-fuel mixture in gasoline engines during compression at low engine speeds and high loads. In this scenario, combustion occurs before the spark plug fires, while the piston is still moving upward. This phenomenon is characteristic of turbocharged, direct-injection gasoline engines, particularly those with small displacement.

LSPI causes sharp pressure spikes in the cylinder, which can lead to severe damage—such as cracked pistons, bent connecting rods, and other component failures—and may even result in catastrophic engine destruction.

A number of industry studies and tests have shown that high concentrations of calcium-based detergent additives increase the likelihood of LSPI, whereas magnesium-based additives have little to no effect on LSPI occurrence. The API SQ requirements have been developed with this factor in mind.

Enhanced Engine Cleanliness

API SQ engine oils are designed to maintain a high level of engine cleanliness, improving performance and extending engine life. This is achieved through the use of next-generation detergent additives and base oils with superior resistance to degradation.

Extended Engine and Component Service Life

API SQ oils provide enhanced wear protection, extending the service life of critical engine components such as the timing chain and turbocharger.

The timing chain requires effective lubrication to reduce friction between links, prevent overheating, wear, elongation, and seizure. Proper lubrication ensures smooth operation, corrosion protection, noise reduction, and improved throttle response. Timing chain elongation disrupts valve timing, while chain failure leads to catastrophic engine damage and costly repairs.

The turbocharger is an expensive and sensitive component. Temperatures in the hot side of the turbocharger, which operates with exhaust gases, can range from 800°C to 1,100°C. Turbocharger rotational speeds may reach 200,000 to 300,000 rpm, depending on engine type and turbocharger design. These extreme conditions impose very stringent requirements on engine oil performance.

Regulatory Compliance

The API SQ standard has been developed in alignment with current industry and environmental regulations.

What’s New and Different About API SQ?

Compared with API SP, API SQ offers significantly improved protection characteristics. The certification process involved updating and enhancing several engine test sequences used to evaluate engine oil performance, including:

Sequence IIH – measures high-temperature viscosity increase and deposit formation.
Sequence VH – evaluates the oil’s ability to control low-temperature engine deposits.
Sequence VI – assesses fuel economy performance.

API SQ oils outperform API SP oils in several key performance areas. In addition, the new category enables the introduction of ultra-low-viscosity oils such as SAE 0W-8 and SAE 0W-12.

Sulfated Ash Limits and GPF Protection

API SQ also specifies a maximum sulfated ash content of 0.9%, comparable to API SP but lower than that of earlier-generation oils. Sulfated ash in engine oils is a primary source of non-combustible metallic residues, typically originating from additive packages.

Ash accumulation can clog gasoline particulate filters (GPFs), which are critical for emissions reduction. Lower ash levels help ensure proper operation and longer service life of emissions control systems, allowing vehicle owners to avoid costly maintenance related to GPF cleaning or replacement.

The Relationship Between API SQ and ILSAC GF-7

The introduction of API SQ coincided with the release of ILSAC GF-7 (GF-7A and GF-7B) standards developed by the International Lubricant Standardization and Approval Committee (ILSAC). API and ILSAC standards are generally closely aligned, including API SQ and GF-7.

However, API SQ covers ultra-low-viscosity grades that are not addressed by GF-7. At the same time, ILSAC GF-7 imposes stricter fuel economy requirements. In most cases, backward compatibility is permitted when manufacturer recommendations are followed—both GF-7 and API SQ oils are backward compatible with vehicles previously requiring GF-6 and API SP oils.

Practical Benefits for Vehicle Owners and the Environment

Passenger vehicle owners will experience several tangible benefits from using these new oil categories, including improved engine efficiency and reduced wear, which help lower maintenance costs and extend vehicle service life. Modest improvements in fuel economy can also be expected.

Drivers can be confident in the proper operation of their exhaust aftertreatment systems throughout their service life. When used within their designed lifespan, these systems operate more reliably and consistently with API SQ oils, contributing to reduced carbon emissions and a lower environmental impact.