Understanding the Newest Motor Oil Standard: What You Need To Know About API SP

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Choosing the right motor oil just got easier. API SP, released by the American Petroleum Institute in 2020, supports both modern and legacy engines. This article cuts through the details to showcase how API SP stands out from previous standards like API SN and enhances your vehicle’s engine performance and life expectancy.

Key Takeaways

  • API SP motor oil, introduced in 2020, offers improved protection against high-temperature deposits, sludge, LSPI, and timing chain wear for both modern and older vehicles due to its backward compatibility with former API categories such as SN PLUS, SN, SM, SL, and SJ.

  • The API SP standard is designed to support the increasing prevalence of turbocharged engines, including those with GDI and T-GDI, and enhances fuel economy, reduces greenhouse gas emissions, and effectively manages renewable fuels, synchronized with ILSAC GF-6A standards.

  • API SP oils are subjected to rigorous testing for high-temperature stability and LSPI prevention, demonstrating significant advancements over previous standards like API SN, even as they maintain operational efficiency and do not affect the performance of older engines without LSPI concerns.

API SP: The Latest Advancement in Motor Oil Standards

A close-up of a car engine with modern motor oil

As motor engines evolve, the motor oil standards need to keep pace. The American Petroleum Institute (API) introduced API SP on May 1, 2020, marking a new era in motor oil standards when API began licensing oils. This new classification demands improvements in areas such as high-temperature deposit protection and sludge control, ensuring enhanced engine performance and longevity.

Notably, API SP motor oil, despite its modern design, does not neglect older models. These oils are backward-compatible, supporting vehicles that previously used API categories like SN PLUS, SN, SM, SL, or SJ, including the API SN category. This compatibility ensures that older engines can also benefit from the advancements that API SP brings.

What Sets API SP Apart from API SN?

The API SP standard is a response to modern environmental regulations, market demands, and technological progress in engine designs. One of the significant improvements it brings over its predecessor, API SN, is its ability to effectively prevent low-speed pre-ignition (LSPI).

LSPI is a serious issue that can lead to severe engine damage. API SP motor oils are specifically formulated to tackle this problem, which API SN did not address as rigorously. This additional protection makes API SP a safer choice for modern engines.

Compatibility with Older Automotive Engines

Backward compatibility is a standout feature of API SP motor oil. Even if your vehicle was designed to use earlier API categories such as SN, SM, SL, or SJ, you can still use API SP oils without worries. This compatibility allows older engines to experience the advancements of the API SP standard.

When selecting API SP motor oil for an older vehicle, you must confirm its backward compatibility with the vehicle’s specified API service category. This step is crucial to ensure the chosen motor oil will provide the necessary protection and performance for your engine.

Engine Performance and Protection with API SP

A fuel-efficient engine with API SP motor oil

If you own a turbocharged vehicle, API SP presents a viable solution. This new standard is specifically formulated to work with turbocharged engines, which are becoming increasingly common in modern vehicles. The advanced formulation of API SP motor oil supports higher efficiency in these engines, including those with Gasoline Direct Injection (GDI) and Turbocharged Gasoline Direct Injection (T-GDI).

API SP not only boosts the performance of modern engines but also enhances their longevity. This motor oil is designed to enhance the protection of key engine components, helping modern engines to operate efficiently and with greater durability. The API SP standard includes new tests for timing chain wear protection, which is important in modern engines due to the shift from belts to chains for increased durability.

Enhanced Fuel Economy and Resource Conservation

API SP motor oils significantly benefit environmental sustainability. They:

  • Help decrease greenhouse gas emissions

  • Improve fuel economy, supporting adherence to environmental regulations

  • Effectively manage renewable fuels in the gasoline supply

API SP offers the following benefits:

  • Boosts fuel economy, leading to improved fuel economy

  • Incorporates a conservation specification, allowing it to effectively handle renewable fuels in the gasoline supply

  • Matches the ILSAC GF-6A standard

  • Offers enhanced fuel economy and protection for vehicles that use ethanol-containing fuels up to E85

High-Temperature Deposit Protection and Sludge Prevention

High-temperature deposit protection for engines

Excessive heat can cause engine deposit and sludge accumulation, potentially compromising your engine’s performance. API SP oils are engineered to enhance high-temperature deposit protection for critical engine components like pistons and turbochargers. These oils undergo rigorous testing to ensure their efficacy in preventing engine deposits and sludge buildup in high-temperature conditions.

API SP motor oils boast advancements in managing sludge and varnish, preserving engine cleanliness and operational efficiency. When compared to the previous API SN standard, API SP represents a leap forward with notable improvements in aspects such as oxidation resistance, wear protection, and deposit control.

Protection Against Low-Speed Pre-Ignition (LSPI)

LSPI can inflict severe damage on engine components like connecting rods and pistons. API SP motor oils are formulated to prevent this in modern engines. They are specifically designed to prevent abnormal combustion events like LSPI, which can cause excessive pressure and permanent damage to engine components.

API SP motor oils are required to pass additional tests for LSPI and timing chain wear protection that are not part of the API SN specification. Even with the reduction in additives like calcium, beneficial for LSPI-prone engines, the performance of oils in older engines without LSPI concerns is not detrimentally affected.

Navigating API Service Categories and Obsolete Ratings

Comparison of current and obsolete API service categories

Knowing the API service categories and their status is vital in choosing the appropriate motor oil for your vehicle. While the latest categories bring advancements in motor oil performance, not all of them may be suitable for your specific vehicle model. Similarly, obsolete ratings, although still available in the market, may not offer the necessary protection for modern engines.

In the upcoming sections, we will explore the present and outdated API ratings for both gasoline and diesel engines. This knowledge will help you make an informed decision when selecting a motor oil that offers optimal protection and performance for your vehicle.

Gasoline Engines: Current and Obsolete API Ratings

For gasoline engines, API offers multiple service categories, with some now being obsolete. These obsolete motor oils are not suitable for use in modern engines due to inadequate protection. Therefore, to avoid issues with inadequate engine protection, it is advisable to use motor oils with the most current API rating.

The current API service categories for gasoline engines include SP, SN, SM, SL, and SJ. API SP oils, for instance, introduced in May 2020, provide protection against LSPI, timing chain wear, high-temperature deposit protection for pistons and turbochargers, as well as stringent sludge and varnish control.

On the other hand, obsolete API service categories for gasoline engines include:

  • SH

  • SG

  • SF

  • SE

  • SD (SD obsolete caution advised)

  • SC (sc obsolete caution advised)

  • SB (SB obsolete caution advised)

  • SA (SA obsolete caution advised)

Each of these categories is unsuitable for use in most gasoline-powered automotive engines built after certain years, ranging from 1930 for API SA to 1996 for API SH, due to inadequate protection against engine sludge, oxidation, or wear.

Diesel Engines: Current and Obsolete API Ratings

Similar to gasoline engines operating, diesel engines have their unique API service categories. The current API service categories for diesel engines include:

  • CK-4

  • CJ-4

  • CI-4

  • CH-4

  • FA-4

Each of these categories is designed to cater to certain emission standards and fuel sulfur content.

It’s important to consult with lubricant suppliers and original equipment manufacturers before switching to CK-4 and FA-4 oils to effectively lubricate engines calling for these specific oils, in order to meet fleet requirements.

On the other hand, obsolete API diesel engine service categories include:

  • CG-4

  • CF-4

  • CF-2

  • CF

  • CE

  • CD-II

  • CD

  • CC

  • CB

  • CA

These categories are an obsolete caution against use in most diesel engines built after specific years.

Each of these obsolete categories, ranging from CA for diesel engines built after 1959 to CG-4 for diesel-powered automotive engines built after 2009, is unsuitable for use. The main reason for their obsolesce is their inadequate protection against certain diesel engine requirements, such as handling high sulfur fuel or preventing engine sludge.

Selecting the Right Motor Oil for Your Vehicle

Consulting the owner's manual for motor oil selection

Selecting the fitting engine oil for your vehicle extends beyond simply opting for the newest API standard or the most advantageous one. It requires an understanding of your vehicle’s specific needs, which can be found in your vehicle owner’s manual. This manual will provide specific motor oil recommendations, including the appropriate SAE viscosity grade.

Despite the multitude of benefits API SP offers, considerations such as fuel efficiency and possible sludge formation in your vehicle’s engine are important. For instance, if your vehicle manufacturer specifies the use of lower-viscosity oils for improved fuel efficiency, select an API SP oil that meets these requirements. Similarly, for vehicles with start-stop technology, select API SP oils that help prevent sludge formation and varnish deposits.

ILSAC GF-6: A Complementary Standard to API SP

Although our emphasis has been on API SP, it’s worth mentioning another standard introduced concurrently – ILSAC GF-6. This standard offers similar improvements and often co-appears on motor oil labels. Developed to enhance fuel economy, reduce greenhouse gas emissions, and cater to the complex demands of new engine technologies, ILSAC GF-6 ensures compliance with environmental regulations.

The launch of the ILSAC GF-6 standard led oil manufacturers to create advanced products capable of meeting the strict requirements set by both ILSAC GF-6 and API SP. ILSAC GF-6 has been split into GF-6A, signified by the ‘starburst’ symbol for backward compatibility, and GF-6B, represented by a ‘shield’ mark, for new low-viscosity oils suitable for newer engines. By targeting the specific requirements of gasoline engines, ILSAC GF-6 ensures that oils with this certification deliver essential protection for these types of engines.


The world of motor oil standards may seem complex, but understanding them is crucial for the health and longevity of your vehicle’s engine. API SP represents the latest advance in motor oil standards, offering enhanced engine performance, improved fuel economy, and compatibility with both modern and older engines. Coupled with the right SAE viscosity grade, as recommended in your vehicle owner’s manual, API SP can contribute significantly to your vehicle’s performance and sustainability. Whether you own a gasoline engine vehicle or a diesel one, knowing the current and obsolete API ratings can guide you towards an optimal choice of motor oil.

Frequently Asked Questions

What does API SP mean?

API SP is the latest engine oil standard issued by the American Petroleum Institute, ensuring high-quality engine oil for your vehicle.

What is the difference between API SN and SP?

The difference between API SN and SP grades is that SP includes all the requirements of SN plus some additional specifications, and SP oils should not be more expensive than SN oils.

Is API SP motor oil synthetic?

Yes, API SP motor oil is a synthetic oil blended from fully synthetic base oils and high-quality additives, allowing for the longest possible service life for engines.

Can I use API SP motor oil in my older vehicle?

Yes, you can use API SP motor oil in your older vehicle as it is backward-compatible with previous API categories.

What are the benefits of API SP motor oils?

The benefits of API SP motor oils include enhanced engine performance and protection, improved fuel economy, and better management of renewable fuels. They also offer high-temperature deposit protection and sludge prevention.

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