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Help reduce emissions, enhance engine performance with low viscosity oils.

May 2, 2024
Stricter federal regulations are reshaping the engine oil industry. PC-12 and low viscosity HDEOs can help with compliance and performance.

In April 2024, the U.S. Environmental Protection Agency announced its proposed “Phase 3 Greenhouse Gas” program, enforcing stricter regulations for heavy-duty vehicles including buses, delivery vans, and commercial trucks, beginning with the model year 2027 and setting new, stricter standards for model years 2028 through 2032. As the largest emissions source in the US, these vehicles contribute disproportionately to the total emissions in the transport sector. EPA’s proposed plan aims to reduce carbon dioxide fuel emissions by almost half by 2045. As a result, the American Petroleum Institute has developed a new heavy-duty engine oil performance category: PC-12. 

Regardless of personal feelings on these “green initiatives,” they are here to stay, and the industry must adhere to these standards. Understanding this new category and how low viscosity HDEOs are helping to shape PC-12 will help you choose the right engine oil to help you comply with these guidelines while enhancing fleet engine performance.

PC-12 and low-viscosity HDEOs

The main way to lower CO2 levels is to improve fuel economy and new low viscosity heavy duty engine oils do just that, by burning less diesel.

In the HD market, SAE 15W-40 had been the workhorse viscosity grade for many years, but it has peaked and is forecasted to decline to nearly 30% by 2029. 

Manufacturers and original equipment manufacturers continue to improve engine and vehicle technology. To support fuel economy drivers and the introduction of new emissions reduction hardware, the American Petroleum Institute (API) introduced CK-4 and FA-4 (PC-11) on December 1, 2016. These standards were eco-friendly and delivered improved engine aeration performance, wear, and deposit protection, oxidation control, and shear stability over API CJ-4. In addition, API FA-4 introduced fuel economy SAE XW-30 grades with high temperature, high shear (HTHS) viscosity range of 2.9cP–3.2cP for fleets’ on-highway applications.

To meet government fuel economy specs, a rapid shift towards SAE 10W-30 is expected. By 2029, SAE 10W-30 may account for roughly 40% of the market and SAE 5W-30, although not reaching mainline volumes, could make up about 10% of the market. API’s proposed PC-12 category (first allowable use on 1/1/2027) may allow the addition of XW-20 viscosity grades.  The growth in use of even lower SAE XW-20 viscosity grades however looks likely to be a slow process that depends on further innovations by HD OEMs.

PC-12 is split in two PC-12 categories, PC12A and PC-12B oils, aligning with the viscosity divide that exists today with API CK-4 and FA-4. This new oil category is bringing key changes to engine and aftertreatment system hardware, including the tightening of the limits for phosphorus, sulfur, and sulphated ash in both PC-12 categories.

As PC-12 keeps developing, much work is being completed to keep the category on track of the desired First Licensed date of January 1, 2027.

Switching to low-viscosity HDEOs

Though you may still be hesitant to use lower-viscosity API FA-4 oils, the good news is that many HD fleet owners and operators are becoming increasingly comfortable with their use. It’s important to emphasize that the use of lower-viscosity oils does not compromise the durability of your engine life or the compatibility of the emissions system. These additives are designed to ensure lubricants can function at much lower viscosities and retain their protective properties even when properly extending draining intervals. 

There are many benefits to switching your engine to a lower-viscosity oil, including improved fuel economy. Advantages include: 

  • Meaningful cost savings. A commercial truck can easily consume more than $70,000 (20,500 gallons) of diesel fuel per year. A switch from 15W-40 to a properly formulated 10W-30 can result in up to 3% fuel savings through outstanding oxidation performance (where OEM recommended). 
  • Improved engine durability, extended engine life, performance, and protection in old and newer engines.
  • Flexible formulation for heavy, medium, and light-duty off-road, and commercial on-road vehicles, as well as stationary diesel engines.  
  • Most products are approved, or suitable, for use in engines by leading heavy-duty engine manufacturers, including Ford, PACCAR, Volvo, Caterpillar, Cummins, Mack, Detroit Diesel, and Mercedes-Benz.
  • Multiple options, such as API CK-4 and FA-4 engine oils to fit your unique fleet and HD operations.

Some HDEOs are guaranteed to reduce total operating costs, improve fuel efficiency, and improve carbon footprint (CITGO offers a Guaranteed Efficiency Program). This results in less downtime and more operating hours.

A balanced formula of calcium and magnesium may be a way to reduce carbon emissions while enhancing engine performance

Choosing an HDEO that delivers the performance needed for newer engine designs while improving performance in older engines is key. Oils with SAE 10W-30 viscosity grade help operators attain new efficiency standards by improving fuel economy and providing superior engine durability.

Premium API CK-4 heavy-duty engine oils like CITGO CITGARD 700 Synthetic Blend Heavy Duty Engine Oil SAE 10W-30 utilize a balanced approach to protect your engine and maintain your Diesel Particulate Filter life. 

What sets this oil apart is its balanced detergent additive package (roughly equal amounts of Calcium and Magnesium detergents) versus many competitors that have Calcium-only detergent packages.  Magnesium ash tends to be more porous and less dense than Calcium ash, which produces the following benefits:

  • Reduced exhaust flow resistance
  • Reduced back pressure (50%)
  • Less workload on engine
  • Improved fuel efficiency

The CITGARD 700 Synthetic blend 10W-30 detergent package also helps maintain engine cleanliness, protects the engine, and maintains DPF life through excellent oxidation control. 

Good oxidation control results in the oil maintaining viscosity throughout the oil drain. In field trial, CITGARD 700 Synthetic blend 10W-30 tested at a 2.1% fuel efficiency savings versus a 15W-40 for the new oil, and after 50,000 miles, the CITGARD 700 10W-30 still showed a 1.8% fuel efficiency savings.

CITGO CITGARD 700 Synthetic Blend Heavy Duty Engine Oil SAE 10W-30 has a successful history with some of the largest fleets in the nation, including J.B. Hunt, Crete Carrier Corporation, and Brundage Bone Concrete Pumping.

As we keep learning more details on the new HD emission requirements, we can expect PC-12 to deliver lubricants with increased wear protection, providing protection for engines working harder under increased operating temperatures. Additionally, since the fuel-saving benefits of lower viscosity lubricants are considerable, lower viscosity grades should continue to grow. 

Contact your supplier about choosing the right balanced formula in heavy-duty engine oils, such as CITGO’s premium line of CITGARD HDEOs, for your fleet operation and emissions compliance. The right HDEO could also help you streamline and simplify your inventory planning and supply needs.

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