While it’s no secret that heavy-duty formulations are changing to incorporate the new API CK-4 and FA-4 categories, here at Kendall we made a commitment to make sure we went the extra mile. Well, actually, we went the extra 67 million miles in the lab and on the road, because that’s how many miles worth of engine testing we ran on our brand new formulations. The results are certainly worth taking a look at.
Every single test conducted using Kendall Motor Oil’s CK-4 and FA-4 formulations proved to vastly exceed API’s performance requirements. Not only that, but post-testing performance analyses showed that engines using Kendall Motor Oil’s updated formulations held far better resistance levels against wear, corrosion, and sludge formation, than engines using our already strong CJ-4 formula.
When it comes to Kendall, seeing is believing. Take a look at those engine parts below. After 540,000 miles of on-road testing, these parts still look and function like they’re fresh out of the factory. Select a part to see how it performed in industry standard bench testing.
Kendall helps valves maintain their precision in regulating intake, combustion, and exhaust.
Advanced Cold Flow
European Engine Formula
Advanced Fuel Economy
Extreme Cold Flow
Advanced Wear Control
Advanced Fuel Economy
1. What do fleets need to know going forward about using CK-4 oils?
a. Simply put, CK-4 oils are the next natural extension of their CJ-4 predecessors with more robust performance in certain categories as demonstrated through a few upgraded API test parameters and a few new OEM tests. CK-4 products are completely back-serviceable to cover all the same diesel applications that CJ-4 did, just with higher performance standards.
There is an additional change that the new specification brings regarding “universal” engine oils (those which claim both “C” categories for diesel and “S” categories for gasoline engines). In order for a diesel engine oil to claim an “S” category, it must now meet all of the gasoline category’s criteria including the limit on phosphorous levels. Phosphorous has long demonstrated proven protective qualities versus ashless chemistries in diesel engines, but has also been known to shorten the life of automotive catalyst systems in gasoline engines. This means that a diesel engine oil must be below 0.08% phosphorous to claim an “S” category approval (the CJ-4 specification allows up to 0.12% phosphorous). The loophole, which used to allow higher phosphorous levels from diesel engine oils when used in gasoline engines, will be effectively closed. In practical terms, this will create a clear line in the sand between diesel-only formulations (“high phosphorous”) and universal oils (“low phosphorous”).
2. What properties make FA-4 better suited for 2017 engines?
a. Over the past 20 years or so, each heavy-duty engine oil category upgrade has focused on reducing emissions. As oils began to reach the limits of their contribution toward lower emissions, engine manufacturers began to design exhaust treatment systems to further reduce NOx and particulates (particulate filters, EGR, SCR and other technologies). Now that diesel emissions have been reduced to historic lows on a per truck basis, the focus has shifted to fuel economy. 2017 engines and the new FA-4 oils are being designed to work together to provide better fuel economy. The major factor distinguishing FA-4 oils from their CK-4 counterparts is that they have lower High Temperature High Shear (or “HTHS”) values. HTHS is an additional measure of viscosity representing internal fluid friction – the lower this value, the better the fuel economy versus an oil of the same kinematic viscosity (expressed as centistokes or “cSt”) with a higher HTHS. In other words, there are SAE 10W-30 oils in both the CK-4 and FA-4 categories with their main differentiator being their HTHS values. Where CJ-4 and CK-4 require a minimum HTHS of 3.5 cP (centipoise), FA-4 oils feature HTHS values in the range of 2.9 – 3.2cP.
3. Explain why CK-4 is a high HTHS formula and FA-4 is a lower HTHS. Exactly what does that mean?
a. It is important to note that there are multiple measures of viscosity – the most common being kinematic viscosity (reported as centistokes [“cSt”] and representing a fluid’s resistance to gravitational flow). Absolute viscosity is another measure which represents frictional drag within the lubricant itself. The lower this value, the less fluid friction. High Temperature/High Shear testing measures the absolute viscosity of a lubricant in a test designed to emulate the area between an engine’s crankshaft and the connecting rod journal bearings in a warmed-up engine. The test is performed at 150°C and its value is reported in centipoise (designated as “cP”). There has been a great deal of testing that shows oils with a lower HTHS can provide improved fuel economy versus oils of the same viscosity with a higher HTHS. As we look at these next generation oils then, the reason for the split categories was to clearly identify products with these different HTHS values. CK-4 require a minimum HTHS of 3.5 cP while FA-4 oils are in the range of 2.9 – 3.2 cP.
4. Explain the viscosities for the new oils. Is all CK-4 oil 10W-30 viscosity? Is FA-4 5W-30 or 10W-30 or both?
a. CK-4 products include all of the legacy viscosity grades including the most popular, 15W-40. FA-4 product viscosities are limited to lower viscosity grades such as 5W-30 and 10W-30. It is possible to have the same viscosity grade offered in both performance categories. For instance, a 10W-30 viscosity grade product can exist in both CK-4 and FA-4 formulations with the difference being a lower HTHS value for the FA-4 lubricants. API has introduced a new donut for the FA-4 specification to clearly identify through wording and color that the category is different.
5. It seems like FA-4 oils are designed for the on-highway haul trucks. What about vocational trucks such as dumps and cement mixers?
a. Given that these are severe-duty applications and the owners are less concerned with fuel economy, is there any reason to use an FA-4 oil in vocational trucks? FA-4 oils may provide fuel economy benefits for all vocations and types of service. However, during the early stages of availability the jury is out as to how many end users will convert. The testing requirements of FA-4 are the same as CK-4, so durability and protection attributes will be robust in both categories. As always, equipment operators need to check with the equipment OEM for recommended viscosity grade and service category information.
6. Are there any concerns about engine performance if these oils are accidentally mixed in an engine?
a. Topping off an engine with CK-4 / FA-4 when the other was called for would not result in anything catastrophic as they both will have passed the same category performance levels. One must always be mindful of maintaining the correct viscosity, though, for proper engine protection.
7. What are the properties that make these two oils effective for their individual applications?
a. CK-4 oils are broadly applicable for on-highway and off-road applications, just like CJ-4, while FA-4 oils are specifically designed to accentuate the fuel economy characteristics of 2017 (and beyond) engine designs. Back-serviceability of the FA-4 oils will be determined by the engine manufacturers. However, it is worth noting that both FA-4 and CK-4 oils will be subject to the same durability testing. As always, fleet operators will need to evaluate their performance and maintenance goals as well as the OEM’s recommendations in order to determine the right mix of products for their equipment.