OEM views on PC-12

The need for longer aftertreatment useful life will create more stringent requirements for oil formulations as some chemicals in engine oils, for example, sulphur, phosphorus and sulphated ash are known to have adverse effects on aftertreatment systems. Our internal study has shown the negative impact caused by those chemicals on aftertreatment components. Reducing the content of those chemicals, while meeting other performance requirements, is critical in meeting those extended aftertreatment useful life goals.

To address this within PC-12, the chemical limits have been lowered for components such as phosphorus and sulphur to protect the future aftertreatment designs. In addition, sulphated ash will be lowered to help extend maintenance intervals.

For model year 2027, Detroit will introduce new engine oil specifications aligned with the launch of PC-12.  To address the increase in full useful life and aftertreatments, Detroit specifications will include limits for potassium and sodium in addition to the PC -12 chemical limit reductions in phosphorus and sulphur. For the increase in full useful life for engines, Detroit specifications will include internal wear tests in addition to the PC-12 wear tests

Oil drain intervals have evolved throughout the years. In today's modern engines, oxidation is the main driver for oil drain intervals rather than TBN. In 2017, Detroit decided to provide longer drain interval options for our customers. Many of our major fleets have taken advantage of these longer intervals because it helps reduce the amount of oil used during the lifetime of the truck and reduces the total cost of ownership for fleets.

An engine oil performance need that is of particular interest to Detroit is oxidation. The limits for oxidation will be tightened in the new PC-12 category. This is important because oxidation is one of the limiting factors for oil drain intervals in modern engines.

In the last five to ten years, the quality of modern oils and improved Cummins engine designs have allowed extended oil drains in service literature across many engine platforms. In addition, Cummins recognised a greater potential for customer specific oil drain extensions based on their unique duty cycle and maintenance programme. We're currently using large data sets from that programme to help pursue new opportunities in the digital space for even greater optimisation.

As greenhouse gas limits become tighter, we expect to see further usage of API FA-4 viscosity fluids. We're validating FA-4 viscosity fluids in many of our highway engine programmes in the years ahead.

Currently we're seeing wider adoption of API FA-4 oils in our engines, but the need to go to lower viscosity oils is not clear.

From our discussions with fleets, the two main topics that come up are longer drain intervals and fuel economy. Longer drain intervals can help fleets achieve reduced downtime and less oil changes to help meet their sustainability goals. As fleets transition to lower viscosity oils such as SAE 10W-30 API FA-4, this will help the fleet improve their overall fuel economy.

The next diesel engine oil category, PC-12, will include an additional viscosity grade SAE XW-20, which is not currently available in API FA-4.

One of the biggest challenges to come is how to educate and prepare the market for the introduction of PC-12. As we learned in PC-11, it is important to start education to the market as soon as possible. From our discussions with fleets, they are excited to learn more about PC-12 and want to help in any way they can to avoid market confusion. 

The challenges remain the same; properly educating the diesel engine oil consumer and the oil changing public. As the NCDT [new category development team] wrestles with the long list of needs that it's addressing, it's clear that added complexity and possibly even separation of on-highway and off-highway needs is forthcoming. It'll be more important than ever to all of us to ensure that these future oils are properly applied and we all have a major role to play in that charge.