The new API oil performance upgrade for heavy-duty diesel engines is here. API CK-4 and FA-4 oils go way beyond their API CJ-4 counterparts, offering greater durability protection and potential for fuel efficiency benefits.
API CK-4 and API FA-4
- About API CK-4 and FA-4
- Market Drivers
The latest heavy-duty engine oil categories of API CK-4 and FA-4 saw first license December 1, 2016.Click here to get an overview of the API CK-4 and FA-4 Specifications in less than two minutes
Previously referred to as Proposed Category 11 (PC-11), and driven by increasingly strict regulatory measures worldwide, this API upgrade focuses on drastically reducing greenhouse gas emissions and improving fuel economy, and emphasizes improvements in oxidation stability, shear stability and resistance to aeration. For the first time in history, in response to the range of viscosity grades in the market, this category upgrade has been split into two. API FA-4 (previously referred to as PC-11B) oils meets developing market needs and API CK-4 (PC-11A) offers backward compatibility in higher HTHS viscosity grades.Key Facts:
- First License date 1st December 2016
- These new oils are simply better than today’s API CJ-4 oils
- Predominantly affects large diesel engines, off-highway vehicles including construction and agricultural equipment
- First time the category has been split. Due to the split, differentiated by their HTHS limit, awareness on using/specifying the correct oil becomes even more critical:
- Backward compatible – minimum 3.5 cP HTHS
- For modern engine designs – 2.9-3.2 cP HTHS
Launched in 2006, API CJ-4 the previous category for engine oil performance, was designed to meet the needs of exhaust emission after treatment technologies, while enhancing engine durability. API CK-4 and FA-4 continues to address those issues while introducing improved performance and an increased fuel economy component. The EMA requested that API CK-4 and FA-4 define improvements in oxidation stability, shear stability and resistance to aeration.
Better fuel economy requires the use of lower HTHS (high temperature high shear) viscosity, fuel efficient engine oils. Today, the U.S. market is dominated by SAE 15W-40 lubricants for diesel engines, but it is likely that, with the advent of API CK-4 and FA-4, we will see an increased use of SAE 10W-30 oils. In response to the range of viscosity grades in the market, for the first time in history, the heavy-duty engine category is split into two: API FA-4 oils will be suitable for both existing and new engines as defined by the respective OEM and API CK-4 offers backward compatibility in higher HTHS viscosity grades.
|See how the category is split into API CK-4 and API FA-4||See how new API categories are developed|
API CK-4 and API FA-4 engine oils will see major upgrades in performance. These oils offer improved fuel efficiency, oxidation performance, shear stability protection and resistance to aeration.
To classify the oils, a rigorous testing process must be undertaken. Figure 1 shows the various tests that have been carried out on lubricants in the past. The current generation does everything the previous generation did, and more.
“Almost all of the tests are carried over from CJ-4. What we’ve added are some more severe tests, such as the Mack T13, which will measure oxidation under higher temperature conditions, better simulating the higher temperatures seen in modern engines," notes Keith Corkwell, Lubrizol's heavy-duty diesel Global Business Manager. “Shear stability has seen a change in blending requirements, to ensure oils are less likely to thin out of grade. The CAT Aeration Test replaces the older Engine Oil Aeration Test (EOAT), which was based on hardware that isn’t available anymore.”
Figure 1: Required testing of Category C oils
Click on the timeline image below to view the specification up to the first licensing date for API CK-4 and API FA-4 oils (December 1st, 2016)
For the first time ever, the National Highway Traffic Safety Administration (NHTSA) and the Environmental Protection Agency (EPA) jointly issued the Fuel Efficiency and Greenhouse Gas Emission Program for Medium and Heavy Duty Trucks. Beginning in 2014, these new regulations account for the specific work done by different types of vehicles, providing unique standards for three categories of trucks. Different CO2 and fuel consumption standards are applied to heavy-duty pickup trucks and vans, combination tractors and vocational vehicles.
Under the new standards, trucks and engines are regulated separately. This posed a challenge for the industry. Both sets of regulations must be considered when equipment is designed, manufactured and installed. In addition, the demands of fleet managers for vehicle and engine improvements to help save on fuel costs without sacrificing engine durability must be taken into account.
The new regulations and fleet manager demands are driving OEMs and engine manufacturers to build new engine technologies, including down speeding, active oil temperature control, advanced combustion design, variable valve timing, and stop-start. These engine designs require commercial vehicle engine oils well beyond the API CJ-4 category.
Therefore, the American Petroleum Institute (API) and the Diesel Engine Oil Advisory Panel (DEOAP) developed a new heavy duty diesel engine oil performance category, due to the wide range of viscosity grades in the market this category was then split into two, which has now become API CK-4 and API FA-4 (Previously known as PC-11A and PC-11B). This commercial vehicle engine oil will yield resistance to aeration, improved fuel economy, oxidation stability, wear and shear stability.
The intensifying demand by end users for ways to save fuel costs and improve efficiency and durability levels in their vehicles is an accelerating trend within the automotive industry. Set against new and more stringent regulations in the emerging and established markets around the world, these factors are the true drivers of contemporary engine and lubricant innovation.
In the US the federal government has, for the first time, adopted an approach of regulating medium- and heavy-duty vehicles and engines for CO2 emissions and fuel consumption. Under the new standards, vehicles and engines will be regulated separately. However, heavy pickups and vans (Class 2b-3) are exempt on the grounds that they may be used for personal transportation, with an annual mileage of only 15,000 miles.
There are separate standards for gasoline- and diesel-powered trucks, but these are not first-time regulations. According to the legislation, these vehicles must achieve a reduction of around 15 percent in fuel consumption and greenhouse gas emissions by model year 2018.
While engines are regulated separately, the standards are not mutually exclusive; they must both be considered during manufacturing and installation. Figure 1 shows the different classes that are considered and how all vehicle types fit into the standards structure.
Figure 1: EPA& NHTSA GHG/Fuel Efficiency Regulation
Vehicle Regulations and Use Charts have been produced in response to a directive from the National Highway Traffic Safety Administration (NHTSA), in conjunction with the Environmental Protection Agency (EPA). This directive concentrates on the need to reduce greenhouse gas emissions, and mandates fuel economy improvements for medium- and heavy-duty vehicles.
Under the terms of the regulations — to be phased in between 2014 and 2018 — different targets will be set, according to the size and weight of the vehicle. Looking solely at on-highway vehicles, the regulations cover combination tractors and trailers, pickup trucks, buses, vans and vocational service vehicles. The EPA has established the CO2 targets, while NHTSA has responsibility for the fuel consumption figures. These are shown in Tables 1 and 2.
|Table 1: Final (MY 2017) Combination Tractor Standards|
|Category||EPA CO2 Emissions||NHTSA Fuel Consumption|
|Low Roof||Mid Roof||High Roof||Low Roof||Mid Roof||High Roof|
|Day Cab Class 7||104||115||120||10.2||11.3||11.8|
|Day Cab Class 8||80||86||89||7.8||8.4||8.7|
|Sleeper Cab Class 8||66||73||72||6.5||7.2||7.1|
|Table 2: Final (MY 2017) Vocational Vehicle Standards|
|Category||EPA CO2 Emissions||NHTSA Fuel Consumption|
|Light Heavy Class 2b-5||373||36.7|
|Medium Heavy Class 6-7||225||22.1|
|Heavy Heavy Class 8||222||21.8|
On the engines side, there are different goals to meet in 2014 and 2017 for three of the different engine types used in vocational vehicles: Light heavy duty (LHD); medium heavy duty (MHD); and heavy heavy duty (HHD). HH gasoline engines are subject to CO2 and fuel consumption targets set for 2016. Table 3 outlines the specific levels that operators need to meet for these vehicles.
|Table 3: Engine Standards for Engines Installed in Vocational Vehicles|
|Category||Year||CO2 Emissions||Fuel Consumption|
|Heavy Heavy Class 8Heavy Heavy Class 8||2014||600||5.89|
|HH Gasoline Engines||2016||627||7.06|
Tractor engines have the same target dates, but with different CO2 and fuel consumption figures for medium- and heavy heavy-duty powerplants. The levels that vehicles powered by these engines must achieve are shown in Table 4.
|Table 4: Engine Standards for Engines Installed in Tractors|
|Category||Year||CO2 Emissions||Fuel Consumption|
|2017||487||4.78 (3.0% reduction)|
|Heavy Heavy Class 8Heavy Heavy Class 8||2014||475||4.67|
|2017||460||4.52 (3.2% reduction)|
NHTSA has announced that its standards will be voluntary in 2014 and 2015; this is to satisfy the lead time requirements under the Energy Independence and Security Act of 2007 (EISA). Both NHTSA and EPA are committed to providing manufacturers with two alternative phase-in approaches that will help achieve the overall reductions by 2018.
The first alternative sees a phased implementation of the final standards, requiring first 15, then 20, 40, 60 and finally 100 percent in each of the model years between 2014 and 2018. The other approach phases the final standards in at 15-20-67-67-67-100 percent, extending the deadline from 2018 to 2019.
Improving durability and optimizing fuel economy are key concerns for fleet managers, given that it is imperative that they maximize uptime and keep operating costs low. It is hoped that the federal government regulations and end user demands will drive engine and lubricant innovations to make this a reality.
One of the major contributing factors is the emergence of API CK-4 and FA-4 for heavy-duty diesel lubricants. Seeing first license in December 2016, these oils will see a marked improvement over their API CJ-4 counterparts, which further benefit operator efficiency and fuel economy.
New engine hardware is forcing lubricant manufacturers to look closely at the products they are creating, with the aim of improving performance, efficiency, and durability.
Vehicle and engine manufacturers are also required to comply with the forthcoming fuel economy regulations for commercial trucks, which have been proposed by the US federal government. At the other end of the spectrum, end users are looking to reduce downtime and save on fuel costs. New engine and lubricant developments are seen as key enablers in allowing such benefits to be realized.
To help achieve this goal, the Engine Manufacturers Association (EMA) requested that the Diesel Engine Oil Advisory Panel (DEOAP) develop an improved next category heavy-duty diesel engine oil. This upgraded API category (previously known as PC-11) was developed and launched in December 2016 and is now known as API CK-4/FA-4. The EMA allowed for two separate and distinct subcategories within the updated category due to many existing engines requiring the current minimum HTHS level to ensure acceptable engine durability. Each category has corresponding HTHS level, one that preserves historical heavy duty oil criteria (API CK-4) and one that provides forward-looking fuel efficiency benefits (API FA-4).
The EMA believes that engine lubricant performance can have a significant influence on an engine’s ability to achieve its fuel efficiency goals, as the fuel efficiency of a heavy duty engine oil is directly related to its high-temperature/high-shear (HTHS).
Under the terms of the agreement, special attention is to be devoted to adopting down-speeding methods in the overall engine design, in order to improve fuel economy for end users.
The need for active oil temperature control (up to 118°C or higher) has also been mentioned in order to further promote fuel economy and to help improve oxidation stability. The added challenges whereby fuel economy is aided by lower viscosity oils, alongside high oil temperatures which make the oils even thinner still, highlights the importance of ensuring component protection continues to be maintained. In addition, the EMA has advised that advanced combustion design should be used alongside variable valve timing and stop-start technologies. All three will have a further positive impact on fuel economy, while the first could also act to influence both wear and oxidation. Variable valve timing can influence aeration, while stop-start can have an effect on wear.
Lubricants play two key roles in the design of new engines; perhaps the most important of these is to act as a technology enabler. Engine advances often come with trade-offs in terms of more severe operating conditions, or extra demands being placed on the lubricant. As a result, lubricant technology improvements are required to provide the basic function of overall system protection. Secondly, the inherent properties of the lubricant can also be seen as a direct contributor to the reduction of fuel consumption.
These benefits can be achieved through a combination of lower viscosity grades and performance additive systems. “One of the ways we know we can get improved fuel economy and lower CO2 emissions is going with a lower viscosity,” comments Shell’s Dan Arcy, global OEM technical manager. “But the real key here is there can be no compromise in the durability of the engine.”
Viscosity will continue to be an important parameter in the future development of lubricants. As an engine pumps lubricating fluid through the main bearings, and the cranks churn through it, a lighter viscosity makes it easier for those parts to move around and the engine burns less fuel as a consequence.
Lower viscosity fluids allow engine components to be moved out of the pure hydrodynamic area and into lower friction regimes. However, great care must be exercised, as these fluids can also move the situation closer to that of boundary lubrication, where friction and wear levels begin to increase once more.
Lubricant additives therefore become essential in the boundary regime, helping to prevent wear and to minimize frictional increases that can occur with a lower viscosity lubricant.