API SA Oils Fail Engine Sequence Tests: A Warning for Modern Engines

Although API category SA oils have been obsolete since the 1940's, they can still be purchased in many discount and convenience stores. Marketers argue the oils offer simple, inexpensive lubrication, but auto manufacturers want consumers to be aware of the risks of using obsolete oils, citing evidence that SA oils are "likely to cause serious damage" if used in engines built since the 1940's.

Industry Testing Reveals Serious Risks

The Alliance of Automobile Manufacturers released a report entitled "Impact of Low Quality Oils on Engine Wear and Sludge Deposits; A Comparison of API SA and API SL (ILSAC GF-3) Engine Oils." It reviews the results of two engine sequence tests run on both an API SA motor oil and an API SL motor oil. According to the report, the SA oil failed miserably in the areas of wear, sludge and deposits.

According to Robert Stockwell of General Motors, the API SA oil failed in many areas and caused filter clogging. "When the pick-up tube plugs, oil starvation will occur on startup and the engine will be destroyed," he said. "Further, the extreme scuffing indicated on five camshaft lobes in the SA test indicate that the life of this engine would be short, regardless of the oil change interval."

The ASTM Sequence VG test measures sludge and deposits. Although the standard test time is 216 hours, the test for the SA oil was cut short at 168 hours because it had already clearly failed. Sludge deposits were evident on the valve decks, rocker arm covers and camshaft baffles at 144 hours, and kinematic viscosity had increased at 168 hours.

The Evolution of Oil Standards: From SA to SQ

Since this study was conducted, oil standards have continued to evolve significantly to keep pace with modern engine technology. The progression of API gasoline engine oil classifications illustrates how motor oil formulations have needed to adapt to increasingly demanding engine requirements:

• API SA (1940s): Obsolete. Contains no additives and provides minimal protection.
• API SL (2001): Introduced for 2001 model year vehicles. Improved oxidation resistance and deposit control.
• API SM (2004): Further improvements in oxidation resistance, deposit protection, and wear protection.
• API SN (2010): Enhanced sludge control, improved fuel economy, and better protection for engines using ethanol-containing fuels.
• API SP (2020): Provided additional protection against low-speed pre-ignition (LSPI), timing chain wear, and improved high-temperature deposit protection.
• API SQ (2025): The newest standard launching March 31, 2025. Introduces even more stringent requirements for engine protection, fuel efficiency, and emission system compatibility for 2026 model year vehicles and beyond.

Similarly, the ILSAC standards have progressed dramatically:

• ILSAC GF-3 (mentioned in the original study)
• ILSAC GF-4 and GF-5 (intermediate standards)
• ILSAC GF-6A and GF-6B (2020): Enhanced protection for modern engine technologies including direct injection and turbocharging. GF-6A covers most viscosity grades and is backward compatible, while GF-6B is specifically for 0W-16 viscosity and is not backward compatible.
• ILSAC GF-7A and GF-7B (2025): The newest standards launching March 31, 2025, alongside API SQ. These introduce even more rigorous performance requirements, including enhanced engine protection, improved fuel efficiency, and stricter controls for emissions and low-speed pre-ignition (LSPI).

Modern Engines Demand Higher Quality Oils

Today's engines are vastly more sophisticated than those of even 15 years ago, with technologies that place even greater demands on motor oil:

Turbochargers

Modern turbocharged engines run hotter and create more stress on motor oil. Turbocharger bearings can operate at temperatures exceeding 300°F and rotate at up to 150,000 RPM, requiring oils with exceptional thermal stability and anti-wear protection.

Direct Fuel Injection

Direct injection systems can lead to fuel dilution in the oil and create more soot, requiring advanced detergent and dispersant additives to prevent deposit formation.

Variable Valve Timing (VVT)

These precision systems rely on oil pressure to function properly and can become clogged or damaged by sludge and deposits, requiring cleaner-burning, more stable oil formulations.

Start-Stop Technology

The increased number of cold starts creates more wear potential, requiring improved cold-start protection.

Extended Drain Intervals

Many modern vehicles now recommend oil change intervals of 7,500-10,000 miles or more, requiring oils with better oxidation stability and longer-lasting additive packages.

The Risk Persists: Low-Quality Oils in Today's Market

Despite advances in oil technology, the risk presented by obsolete or inadequate motor oils hasn't disappeared. In fact, as engines have become more sophisticated and tolerances tighter, the potential damage from using inferior oil has only increased.

The findings from the Alliance of Automobile Manufacturers' study remain relevant today, even though oil standards have progressed dramatically from SL to the current SP and upcoming SQ classifications. If an obsolete SA oil caused significant damage to engines designed for SL oils, imagine the potential harm to today's advanced engines designed for SP or SQ-rated oils.

Some discount retailers and convenience stores still sell motor oils that fail to meet current API standards. These products may be marketed with attractive pricing, but the potential cost to your engine far outweighs any initial savings.

How to Protect Your Engine

To ensure your engine receives proper protection, follow these guidelines:

1. Check the API Donut: Look for the API service symbol (donut) on the oil container. For gasoline engines, the current standard is API SP, with API SQ launching in March 2025. For diesel engines, look for API CK-4 or FA-4.
2. Look for the ILSAC Starburst: The International Lubricant Standardization and Approval Committee (ILSAC) starburst symbol indicates the oil meets the current GF-6 standard (or soon, GF-7) for protection and fuel economy.
3. Follow Manufacturer Recommendations: Your vehicle's owner's manual specifies the correct oil viscosity and minimum quality standard required for your engine.
4. Consider Synthetic Oils: For the best protection, especially in modern engines, premium synthetic oils like AMSOIL offer superior performance in all the critical areas that obsolete oils fail – wear protection, deposit control, and thermal stability.
5. Avoid "Too Good to Be True" Bargains: Extremely low-priced oils may use obsolete formulations or substandard base stocks and additive packages that don't provide adequate engine protection.

AMSOIL: Exceeding Modern Oil Standards

While today's minimum oil standards have improved significantly since the SA classification, leading synthetic oils like AMSOIL go far beyond these minimum requirements. AMSOIL Signature Series Synthetic Motor Oil, for example, not only meets but exceeds the requirements of the current API SP and ILSAC GF-6 specifications, providing:

• 75% more engine protection against horsepower loss and wear than required by a leading industry standard*
• Protection for vital engine parts from heat and wear, even in extreme conditions
• 50% more cleaning power than required by the industry standard
• Extended drain intervals up to 25,000 miles/one year (in normal service)

As the industry transitions to the newer GF-7 and API SQ standards in 2025, AMSOIL remains at the forefront of lubricant technology, ensuring their formulations meet or exceed these increasingly demanding specifications.

*Based on independent testing of AMSOIL Signature Series 5W-30 in the ASTM D6891 test as required by the API SN specification.

Conclusion: The True Cost of Cheap Oil

Citing the industry tests as proof that SA oils are harmful to modern engines, the Alliance of Automobile Manufacturers has worked to spread the word to consumers about the dangers of obsolete oil classifications. Though regulations and awareness have improved since the original study, the fundamental risk remains the same: using inadequate oil in your engine can lead to accelerated wear, sludge formation, and potentially catastrophic engine failure.

When considering motor oil, remember that the few dollars saved by purchasing obsolete or inferior oil can potentially cost thousands in engine repairs. For modern engines—especially those with advanced technologies like turbochargers, direct injection, and variable valve timing—using a high-quality oil that meets or exceeds current specifications isn't just recommended; it's essential for long-term reliability and performance.

For more information about modern oil standards and how they impact your vehicle's performance and longevity, check out our articles on lubricant testing and specifications and why premium synthetic oils like AMSOIL provide superior value.

I hope that this information is useful to you and answers your questions. I am here to help and answer any additional questions you may have, whether it be oil related or any other component or system on any snowmobile, car, truck or other equipment. Feel free to contact me for personalized recommendations for your specific vehicle.