PC-12 Engine Oils: Navigating Change with Confidence

The introduction of PC-12 heavy-duty engine oil standards represents one of the most significant shifts in the industry to date. Driven by stricter EPA and CARB regulations, these changes aim to improve fuel efficiency, enhance engine protection and reduce greenhouse gas emissions. This will mark a pivotal evolution in how heavy-duty engine oils are formThe introduction of PC-12 heavy-duty engine oil standards represents one of the most significant shifts in the industry to date. Driven by stricter EPA and CARB regulations, these changes aim to improve fuel efficiency, enhance engine protection and reduce greenhouse gas emissions. This will mark a pivotal evolution in how heavy-duty engine oils are formulated and used, reflecting growing demands for both environmental responsibility and performance improvement.ulated and used, reflecting growing demands for both environmental responsibility and performance improvement.

PC-12 standards come at a time when the transportation and logistics industries face increasing pressure to decarbonize. For fleet operators and OEMs, this shift means adapting to new formulations that balance enhanced engine protection with sustainability goals. It's not just about meeting regulatory requirements-it's about leveraging these changes to gain a competitive edge and improve long-term operational outcomes.

What is PC-12?
PC-12, or Proposed Category 12, represents the next generation of heavy-duty engine oil standards developed by the American Petroleum Institute (API). These standards are being introduced to meet evolving industry demands for improved engine performance, fuel efficiency and reduced environmental impact. Set to launch in 2027, PC-12 builds upon the advancements of previous categories like PC-11, focusing on supporting newer engine technologies and stricter emissions regulations.

Key Innovations
PC-12 oils will emphasize advanced formulations to meet the needs of modern engines:

  • Lower Viscosity Grades: Lower viscosity oils reduce friction and improve fuel economy while maintaining engine protection, especially under high pressure and extreme temperatures.
  • Enhanced Oxidation Resistance: New formulations provide better resistance to thermal breakdown, supporting longer drain intervals and reducing maintenance frequency. By extending oil drain intervals, fleets can minimize downtime and lower overall maintenance costs, contributing to improved operational efficiency.
  • Improved Wear Protection: Additives are optimized to prevent wear under higher loads, helping extend engine life.

Categories
PC-12 standards are designed with the diverse needs of on-highway and off-highway fleets in mind. To ensure seamless adoption and maximum utility, PC-12 will be divided into two distinct categories:

  • PC-12A: Backward-compatible with legacy equipment, offering fleets continuity and ease of transition. This category ensures older, high-mileage engines continue to perform reliably while meeting modern regulatory standards. For fleets with mixed equipment profiles, PC-12A provides a seamless solution that protects existing investments while aligning with future-focused operational goals.
  • PC-12B: Specifically developed for advanced engines with stricter requirements, ensuring top-tier performance for next-generation equipment. This category is ideal for fleets looking to future-proof their operations. The newly allowable XW-20 viscosity grades will help over-the-road fleets optimize fuel economy.

Understanding the differences between PC-12A and PC-12B will empower fleets to make informed decisions that align with their specific equipment profiles and operational goals.

Testing and Validation
Air contamination can have negative effects on the machine and the lubricant. Air can damage a lubricating oil by increasing the rate of oxidation and thermal degradation, depleting additives, reducing its heat transfer coefficient and reducing its film strength. Oil can oxidize when its molecules come into contact with oxygen. It stands to reason that the more oxygen that exists in the oil, the faster the oil will oxidize. This problem is exacerbated when the bubbles move into high-pressure environments where the change in volume causes a drastic increase in temperature. The process, sometimes called microdieseling, causes thermal degradation of the oil as well.

Machine wear can be generated by air contamination by several mechanisms. For one thing, air is compressible. In order for the oil to create the appropriate lubricating film thickness, it must be incompressible. When the oil is heavily contaminated with entrained air, its film strength can be reduced to the point where the film breaks down, allowing metal-to-metal contact between interacting surfaces. Depending upon the type of machine, this effect could be rapid.

In machine environments where dramatic pressure changes occur, such as a hydraulic pump, the dramatic and instantaneous volumetric change causes bubbles to implode violently, which leads to the erosion of machine surfaces. In hydraulics, entrained air can create other problems as well, such as spongy operations, loss of control, and an increased likelihood of surface deposits in valves.

Identifying and Controlling Air Contamination
PC-12 oils will undergo rigorous testing, including engine-specific evaluations such as:

  • Detroit DD13 Scuffing Test: This test evaluates an oil's ability to protect against scuffing and wear under high-friction conditions. With modern engines operating at higher loads and pressures, the scuffing test can tell you if PC-12 oils provide sufficient lubrication to prevent metal-to-metal contact, which can lead to damage and reduced engine lifespan.
  • Cummins ISB Viscosity Test: This test validates that oils maintain optimal viscosity across a range of operating conditions. Modern engines demand consistent lubrication performance and pumpability at both high and low temperatures.

Rigorous testing will ensure PC-12 oils meet the demands of modern engines, which operate under higher thermal and mechanical stresses due to stricter emissions standards and advanced hardware. Most importantly, they will also protect sensitive after-treatment systems, such as diesel particulate filters (DPFs) and selective catalytic reduction (SCR) systems, by minimizing ash formation and preventing deposit buildup, ensuring compliance with emissions regulations.

Additionally, PC-12 oils are being tested to support longer drain intervals, resisting oxidation, thermal breakdown and viscosity loss over time. This will reduce maintenance costs and downtime while maintaining engine protection. By simulating real-world operating conditions, these tests confirm the oils' reliability across diverse environments and applications, giving fleet operators confidence in their performance and durability.

Innovating for Efficiency and Sustainability
PC-12 oils will introduce innovations that prioritize both efficiency and sustainability. Lower viscosity grades, such as SAE XW-20, will be key drivers of improved fuel economy and reduced greenhouse gas emissions. These formulations not only meet stringent regulatory standards but also align with fleet goals to lower the total cost of ownership by delivering measurable fuel savings across diverse fleet sizes.

PC-12 oils will introduce innovations that prioritize both efficiency and sustainability. Lower viscosity grades, such as SAE XW-20, will be key drivers of improved fuel economy and reduced greenhouse gas emissions. These formulations not only meet stringent regulatory standards but also align with fleet goals to lower the total cost of ownership by delivering measurable fuel savings across diverse fleet sizes.

CITGO® Lubricants: A Trusted Guide in a Time of Change
CITGO Lubricants serves as a trusted partner for fleets and OEMs by providing tailored solutions that simplify compliance with evolving emissions regulations. CITGO Lubricants is working to develop innovative next generations of CITGO CITGARD® & Mystik® JT-8® Heavy Duy Engine Oils that will support customers in meeting stringent standards such as those set by PC-12 and GHG Phase regulations, offering advanced formulations that improve fuel efficiency, reduce emissions, and protect engines.

PC-12 Specific Milestones (2025 - 2027)

1. 2025 - PC-12 Tech Demo & Limit Setting:
The industry must prepare for PC-12's stringent oil performance standards, ensuring they are ready for the first allowable use in 2027.

Support: CITGO Lubricants has participated in early PC-12 testing and product development, ensuring that our engine oils wil meet and exceed the upcoming standards, providing better protection for heavy-duty engines.

2. 2026 - Mandatory Waiting Period:
This period allows customers to evaluate their fleet's readiness for PC-12 standards and make necessary adjustments to meet compliance.

Support: CITGO Lubricants will offer educational materials and technical support during this period, helping customers make informed decisions about transitioning to PC-12-compliant oils.

3. January 1, 2027 - PC-12 First Allowable Use:
From this date, fleets can use PC-12-compliant oils to maintain compliance with emissions and performance standards.

Support: CITGO CITGARD and Mystik JT-8 Heavy Duty Engine Oils will be fully PC-12-compliant, offering customers peace of mind with premium products that protect their engines and maximize efficiency under the new regulations.

Bottom Line
PC-12 marks a pivotal step forward for the heavy-duty engine oil industry, driven by regulatory advancements and the pursuit of efficiency and sustainability. For fleet operators, this change means an opportunity to adopt advanced formulations that provide better engine protection, lower costs and align with broader environmental goals. Upcoming PC-12 solutions from CITGO Lubricants will provide fleets with the tools they need to navigate these changes confidently, ensuring compliance and operational success.

Stay up to date on PC-12 engine oils from Mystik Lubricants at the Resource Center

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