Delivering More with Every Drop: A New Era for Heavy-Duty Engine Oils

The heavy-duty engine oil (HDEO) industry is on the brink of a transformative shift with the development of the new API Proposed Category 12 (PC-12), targeting first licensing by January 1, 2027. This upcoming category introduces advanced chemistries and next-generation formulations designed to meet evolving performance and regulatory demands.

Afton Chemical is leading the charge with HiTEC® 12330 and HiTEC® 12380 HDEO additive series. These formulations are engineered to meet updated sulfated ash, phosphorus, and sulfur (SAPS) requirements while delivering enhanced performance in four key areas:

• Increased oxidation stability
• Lower high-temperature high-shear (HTHS) viscosity
• Wear protection
• Improved aftertreatment system (ATS) compatibility

PC-12: A Performance Leap Forward

PC-12 builds on the foundation of current categories—API CK-4 and API FA-4—and introduces two subcategories:

• PC-12A: Successor to API CK-4, maintaining traditional viscosity limits and backward compatibility.
• PC-12B: Evolves from API FA-4, retaining 2.9–3.2 HTHS for xW-30 grades and introducing 2.6 HTHS for xW-20 grades, pushing boundaries in fuel economy and emissions.

 

Formulating for the Future

Afton’s R&D team has meticulously selected components to optimize performance under PC-12’s stricter SAPS limits. One major change is a ~35% reduction in phosphorus, traditionally supplied by ZDDP—a key antiwear and antioxidant agent.

To overcome this challenge, Afton has developed synergistic chemistries that maintain wear and oxidation protection. Testing has shown that even with 12% lower phosphorus than PC-12’s minimum, performance remains robust in Cummins ISM and ISB wear tests and oxidation trials.
 

Exploring Low HTHS Viscosity Grades

With PC-12B introducing low HTHS SAE xW-20 grades, Afton has proactively tested extreme scenarios. An experimental SAE 5W-16 (2.4 HTHS, 0.06 wt.% phosphorus) prototype—25% below the phosphorus limit—was evaluated for wear performance, offering valuable insights into wear mechanisms and formulation strategies.

Following this, a SAE 5W-20 (2.6 HTHS) prototype underwent a 550,000-mile field trial with no performance issues, demonstrating real-world viability.
 

Enhancing Aftertreatment System Compatibility

Unlike previous upgrades, PC-12 places a strong emphasis on ATS compatibility, especially for Class 8 on-highway vehicles. With the EPA’s 2027 NOx regulations increasing emission warranty (EW) and emissions useful life (EUL) requirements, oils must now support longer-lasting ATS performance.

Afton’s research highlights that it’s not just SAPS levels, but their chemical nature—particularly sodium (Na) and potassium (K) from detergents—that can impact Selective Catalytic Reduction (SCR) efficiency.

Through collaboration with ATS experts and rigorous testing, Afton screened formulations for catalyst compatibility and validated performance using the Diesel Aftertreatment Accelerated Aging Cycles (DAAAC) protocol developed by SwRI. Our PC-12 formulation exceeded the 2027 EUL target of 650,000 miles, achieving 800,000 miles while still meeting NOx emissions standards.
 

Field-Proven Performance: Going the Extra Mile

Over the past five years, Afton’s Heavy-Duty R&D, Marketing, and Field Engineering teams have worked closely with fleets to understand operational challenges. Their feedback was clear: “Keep my vehicle running.”

In April, Afton delivered on that promise with a PC-12 prototype that achieved three consecutive 90,000-mile oil drain intervals (ODIs), plus the standard 60,000-mile ODI —totaling over 500,000 miles without issues. This SAE 10W-30 API FA-4 formulation, made with 100% Group II base oil, is now being tested for 100,000-mile ODI capability, with the first milestone expected by year-end.
 

Delivering Passion for Solutions®

At Afton, our commitment to Passion for Solutions® drives us to deliver more with every drop. The HiTEC® 12330 and HiTEC® 12380 HDEO additive series are not only built to meet PC-12 standards—they’re proven to exceed them through rigorous lab testing and real-world validation.
 

Want to learn more about PC-12? 

Click here for the full article or contact your Afton Chemical Sales representative today and discover how our next-generation solutions can help your customers go further, cleaner, and more efficiently.