PC-12 Update

Meeting stricter emission control requirements

Truck Truck

It has been a little over a year since we first reported on PC-12, the industry initiative to develop new API heavy duty oil categories. “PC” stands for “proposed category,” and “12” simply indicates that this is the twelfth iteration of the American Petroleum Institute’s oil service classifications. Advancements in engine technology, necessitated by new emission control and fuel efficiency regulation, are the chief drivers of the development of a new oil category. The PC-12 initiative was launched at the request of heavy-duty engine OEMs in anticipation of more stringent regulations coming into effect in the 2027 model year. Just as engines have to evolve, so do the lubricants that help them function properly.


As of January 2024, the standards are essentially finalized, and engine builders are starting to accelerate the development of new hardware to meet them. The most critical requirements coming in 2027 include a huge reduction in nitrogen oxide (NOx) emissions, 75% lower than currently allowed and capped at 0.035 grams per horsepower-hour. In addition, Class A trucks will now be required to stay compliant with the new emission standards for 800,000 miles, a near doubling of the current useful life requirement of just over 400,000. For lubricant producers, the standards also call for further reductions in phosphorous and sulfated ash that can impair emission control systems and diminish fuel economy.


Along with the federal mandates, the California Air Resources Board (CARB) is rolling out its Clean Truck Check program, in which class 4 and higher trucks must undergo two emissions inspections per year, with a $30 compliance fee. All of this is driving engine design changes and after-treatment system improvements to meet the stricter emissions limits, which in turn drives the need for new oil categories.


As with the last major category introduction, PC-11, PC-12 will actually result in two categories, which will likely be called CL-4 and FB-4. The CL-4 standard will require oils to be backward-compatible with earlier generations of engines. One of the requirements we have is to account for the needs of fleets that have a mix of older and newer vehicles, and to be mindful of the off-highway segment that does not have the same fuel economy demands as on-highway trucks. CL-4 oils will be targeted to the same industry segments currently being served by CK-4 oils.


The FB-4 category is intended to advance thinner-viscosity oils that help promote fuel economy in the newer model engines now in development. Within this category, we are looking closely at the potential for SAE 20-weight oils, which will be a big step for the industry. While this concept is new to us in North America, Europe has been a few years ahead of the curve in the adoption of 20-weight viscosity grades. Some OEMs now require 0W-20 viscosities in their factory fill lubricants. U.S. OEMs that have partners or working relationships with European engine builders are studying their experience carefully and applying those learnings in their new engine designs.


Chevron has been working on PC-12 for more than two years and has made significant headway. We have partnered with engine manufacturers to understand their plans and needs, and what their new engine technology will mean for lubricants. At the same time, we have been collaborating with our additive partners who provide the “building blocks” of our finished oil formulations.


When we develop new oils that will help meet stricter emission standards, Chevron sees it as an opportunity to make other improvements to our formulations that will have meaningful benefits to the end users. For example, we are looking at incorporating greater oxidation stability under the new standards, which may enable OEMs to extend their recommended oil drain intervals – oxidation being the key determinant of oil life. The combination of improved fuel economy, longer oil life and fewer oil changes should be beneficial to our fleet customers’ bottom lines.


The framework for PC-12 is now firmly in place. We know the chemical limits for our formulations, we know the specific tests that are required, and we are gearing up to begin manufacturing in the coming years, with an eye toward having product available by the first license date in January 2027. That many sound like a long way off, but in the lubricant world, we see that as an aggressive timetable, and we are working diligently with our industry partners to meet it.  


Shawn’s career spans 28 years focused exclusively on research and engineering dealing with heavy-duty engine lubricants, fuels, emissions, and materials. Before joining Chevron in 2013, he spent 12 years leading global fluids and materials engineering activities for Cummins. He also spent five years conducting lubricant, fuel, and emission research for the Department of Energy’s National Renewable Energy Laboratory in Golden, CO. At Chevron, he is a Principal Engineer primarily responsible for product formulation of the Delo Brand of Heavy Duty Engine Oils. Whitacre is the chairman of the ASTM Heavy-Duty Engine Oil Classification Panel, which was tasked with the final development of the API CK-4 and FA-4 specifications that took effect in late 2016.

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