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New diesel engine oil category: On the road to PC-12

30 March 2022

The need to meet the upcoming US 2027 emission regulations for NOx and GHG is driving change to heavy-duty diesel hardware. To ensure lubricants continue to deliver sufficient engine and aftertreatment protection, the Truck and Engine Manufacturers Association (EMA) has requested a new heavy-duty engine oil performance category, PC-12, that will supersede the existing API CK-4 and API FA-4 categories.

PC-12 is likely to bring two new sub-categories to heavy-duty engine oils, according to Infineum Insight. These will align with the viscosity divide between API CK-4 and FA-4, which associates fuel efficiency with the corresponding performance levels.

The first sub-category retains the existing heavy-duty oil criteria of a minimum of 3.5 cP HTHS and will be backward compatible to older categories: API CH-4, CI-4 (PLUS), CJ-4, CK-4. The second lower viscosity category provides fuel efficiency benefits while maintaining durability. This is expected to extend down to 2.6 cP HTHS, enabling the use of SAE XW-20 viscosity grades, and go up to 3.2 cP HTHS to align with the current API FA-4 category. Since its target use is in engines with modern and future aftertreatment systems (containing an SCR catalyst) it requires less viscosity control for soot. The second category will not be backward compatible with older categories.

EMA has also requested additional wear performance through the new Ford 6.7L Valvetrain Wear Test and the Detroit Diesel DD13 Scuffing Test; better oxidation performance to help maintain oil drain intervals for hotter engines; and possibly tighter chemical limits to help protect aftertreatment systems, targeting levels of 0.08%m phosphorus and 0.3%m sulphur.

In addition to developing new tests, there is also a need to deal with aging engine tests that are reaching the end of their lives. Here API is assessing the Mack T-11 and Mack T-12 tests and is looking at replacement options for them for PC-12 and for the older API categories.

Source: Infineum Insight