PC-12 latest update

New regulations in North America will introduce large emissions reductions for Model Year 2027 on-road commercial vehicles, driving change to engines and aftertreatment systems. The new PC-12 engine oil performance category is being developed to ensure heavy-duty engine oils continue to deliver sufficient protection to this evolving hardware. There is still work to be completed to keep the new category on track for the desired First License date of January 1 2027.

Let’s start this update by looking at some of the major changes coming in for the new category.

One of the big changes is the introduction of tighter chemical limits for phosphorus, sulphur and sulphated ash in both the PC-12A and PC-12B categories. The new limits are designed to help protect advanced aftertreatment systems that are needed to enable MY 2027 vehicles to meet the new emissions standards.

Another big change is the introduction of lower viscosity grades (SAE XW-20). This action is designed to help support fuel economy improvements and to help reduce greenhouse gas emissions. In addition, oxidation performance and wear protection have been improved with tighter Volvo T-13 limits and the addition of the Detroit DD13 scuffing test.

The request for the protection for hydrogenated nitrile seals has been handled, with the addition of a new hydrogenated nitrile butadiene rubber (HNBR) material. While it’s been reported that testing on this seal has finished, as yet no proposed limits have been provided.

The two PC-12 categories

PC-12 is split into two categories that align with the viscosity divide that exists today with API CK-4 and FA-4, as shown below.

As with the prior specification, there will remain no direct connectivity between the API “C” and “F” categories. Something to note here is that the PC-12A specification is expected to be fully backward licensable to prior active API “C” specifications. API and EMA are discussing how to handle back licensability to the current FA-4 category for the PC-12B specification, due to the change in the viscosity control for soot parameter. It is likely that the two new category names will be API CL-4 (for PC-12A) and FB-4 (for PC-12B), but this will not be confirmed until they are approved by API and written into API 1509.

PC-12 tests

A number of changes to the tests for PC-12 are being made and a summary of what can currently be expected is shown in the table below. While we have included the target values (shown in red) for information, the actual pass/fail limits will not be set until after the technical demonstration period. A point to note here is that we might expect the limits for the Soot Viscosity in EGR engines (ISB Viscosity test) to change from the originally proposed targets noted below due to some performance differences of this new replacement test.

Enlarge view

Progress on new and replacement tests

BOI/VGRA matrix for the new Detroit Diesel DD13 Scuffing Test started in August/September this year. The test, which already holds an ASTM method (ASTM D8074), has been included to address concerns around scuffing in the power cylinder with lower viscosity fluids, and will be introduced into the category with its current low viscosity reference oil.

The development of the Cummins ISB viscosity test that will be used for PC-12 has progressed well. The test procedure has been set and it has been through the precision matrix, which completed on June 10 2024. The test will support the diverging soot handling targets of the two PC-12 categories through two distinct methods. One will be used to support the “C” category (PC-12A), this method targets a range of soot at 156 hours. The other will be used for PC-12B, while it uses the same method, it ends at 108 hours. BOI/VGRA is expected to start in October after stands are referenced and is scheduled to be completed around year end 2024.

Currently the industry is running base oil interchange and viscosity grade read across (BOI/VGRA) matrices for both of these new tests. These matrices will look at VGRA from SAE XW-20 through 15W-40 viscosity grades and at BOI between Group II / Group II base stocks and Group II / Group III base stocks.

New reference oils

The Cummins ISB wear reference oil is at the laboratories, where we expect testing to be run through October/November. The results of the Cummins ISB reference oil in the Cummins ISM test, which should be available shortly, will decide if it would also be a good choice for the Cummins ISM test.

While the Volvo T-13 reference oil is now available, it has been battling oil consumption issues. The Surveillance Panel is vetting a potential solution which, if successful, would allow testing to be completed on the new reference oil.

We will keep you informed of progress on these issues as we get more information on the testing outcomes.

Looking ahead

With most of the timeline critical items progressing, we are currently on track to meet the proposed First License date of January 1 2027.

The big items still left to complete are finishing the BOI/VGRA matrices and completing the reference oil matrices. Technology demonstration is expected to start at the beginning of 2025, but all of the tests need to be available for candidate testing at the labs before this can commence.

Infineum is hard at work developing oils and testing them, both in the engine tests and in field, to get them ready for MY 2027 vehicles. Please contact your Infineum representatives to learn more about our progress.

Infineum Insight will keep you informed of PC-12 progress – sign up here to receive regular updates to your inbox and visit our PC-12 resource hub for more information.

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