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Your vehicle’s engine oil makes a big difference in how it operates—and it affects systems other than the engine, too. For instance, many diesel truck owners hate their rig’s diesel particulate filter, and they might not even know their oil could be clogging it with soot faster. Well, with some upcoming blends in the heavy-duty API PC-12 category, that problem could soon be addressed.
Shawn Whitacre, principal engineer at Chevron Lubricants, talked about this in a recent episode of The Diesel Podcast. He explained that diesel exhaust and after-treatment systems have greatly influenced how they make engine oil. Essentially, because these emissions-control components have proven quite fickle in the real world, they’ve had to reduce oil additives like sulfated ash to keep them from plugging up.
“It was at that point [when DPFs were introduced, between 2007 and 2010] we had to start learning how to do more with less,” Whitacre explained. “We actually had to, by requirement, start taking additive out and rebalancing these packages because there’s some amount of lube oil that gets consumed in the course of operation and ends up in the exhaust.”
“We started having to reduce what we call sulfated ash levels and produce other componentry that is known to affect the performance of those after-treatment systems,” Whitacre continued.
Chevrolet
The new PC-12 oil category takes this a step further while remaining backward compatible, as it’s suitable for engines from 1998 on up to today. Rather than relying on zinc and phosphorus for anti-wear, or calcium and magnesium for acid neutralization—both of which produce ash that clogs DPFs—oils like Chevron’s new Delo 600 family use synthetic dispersants and non-metallic anti-wear agents. This should lead to smoother operation and, hopefully, less frequent DPF regeneration events.
The American Petroleum Institute approved the PC-12 category license earlier this year to meet EPA 2027 heavy-duty engine regulations. Engine manufacturers are required to drastically reduce particulates by 50% and nitrogen oxide emissions by as much as 90% from current limits, and doing so has required reworking DPFs, exhaust gas recirculation systems, selective catalyst reduction equipment, and so on. A new oil category was necessary to help these engine makers hit their goals.
These symbols will be displayed on PC12 oil containers to help customers identify the two categories: FB-4 and CL-4.
While these regulations specifically affect heavy-duty diesel engines, the oil in question also applies to light-duty trucks that run a Cummins, a Ford Power Stroke, or a GM Duramax. Specifically, owners of those pickups should look for API CL-4 oils, as those are engineered with high-temperature, high-shear viscosity profiles; meanwhile, API FB-4 oils have ultra-low viscosity, which might be too thin for those engines’ pumps, bearings, and clearances.
Expect to see these oils hitting the shelves on January 1, 2027, when EPA 2027 standards take effect.
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From running point on new car launch coverage to editing long-form features and reviews, Caleb does some of everything at The Drive. And he really, really loves trucks.
