The US Environmental Protection Agency (EPA) released new regulations that require engine manufacturers to meet stringent emissions standards. These regulations will come in 2027 and will affect Model Year 2027 engines. These changes will mean that heavy duty diesel engine oil will need to change to help engines operate more efficiently to meet new federal standards. The 2027 standards also call for a 75% reduction in nitrogen oxide (NOx) and a 50% reduction in particulate matter. These new standards will also require after treatment systems (diesel particulate filters, or DPFs) to effectively double their useful life, from 450,000 miles to 800,000. With this in mind, engine manufacturers made a request for a new engine oil category to help facilitate the changes needed to meet the new regulation and ensure a smoother transition for 2027. This new engine category is called Proposed Category 12 (PC-12) and was formally endorsed by the American Petroleum Institute (API) back in 2022. Similar to the PC-11 facilitating hardware improvements in 2016, the PC-12 engine category will enable further advancements in engine technology. Staying informed about these updates is crucial to ensuring that your engines remain compliant with the latests standards and operate efficiently under new regulations.