Can 0W-20 Oils Protect Heavy-duty Diesel Engines?
Will heavy-duty diesel engines be guarded by 0W-20 oils?
As fuel economy goals and pollution regulations become more stringent globally, there has been a growth in the need for lower-viscosity heavy-duty engine oils to help meet these criteria. Lubricant formulators are working to further reduce viscosity, despite the fact that many fleet owners and operators have been sluggish to switch to the lower-viscosity engine oils that are now on the market.
In a presentation at the Society of Tribologists and Lubrication Engineers' Annual Meeting and Exhibition in May, John Pettingill, R&D product specialist for Petro-Canada Lubricants, mentioned that the company has developed and tested two 0W-20 heavy-duty diesel engine oil prototypes.
Heavy-duty engine oils, in Pettingill's opinion, are crucial for safeguarding and extending the life of heavy-duty diesel engines. As a result, the following qualities must be included in heavy-duty diesel engine lubricants at a minimum:
Despite all of these aspects, the engine oil itself must nevertheless maintain its fundamental performance characteristics. It must "resist change in viscosity, so that it doesn't go too much over or below its intended and stated grade," according to Pettingill. " It must control oxidation, which is more important now than ever because engines are operating at higher temperatures. It must be able to endure volatility in order to keep its liquid state and prevent vaporizing at high temperatures. Above all, it must function at a variety of temperatures. Multi-grade oils must offer protection at both extremely low and exceptionally high temperatures.
So why is low viscosity heavy-duty motor oil necessary for the market?
Low viscosity engine oils, according to Pettingill, "provide greater fuel economy." API FA-4 products are at the moment the lowest viscosities allowed for API-licensed and OEM-approved heavy-duty diesel engine lubricants in the North American market. Their high thermal and high shear limits of 2.9 to 3.2 centipoise serve as their defining qualities. They are available in viscosity classes of 5W-30 and 10W-30. Your HTHS simulates viscosity at high temperatures and under demanding situations.
More traditional heavy-duty engine lubricants must have an HTHS of 3.5 cP or above in accordance with the oil's viscosity rating or OEM requirements. Pettingill suggests that the minimum needs for a 15W-40, for instance, may be 4.2.
In addition to better fuel economy, lower-viscosity engine lubricants also offer reduced operating costs and improved exhaust emissions, according to Pettingill. He said, "You're burning less fuel, thus there are fewer pollutants."
How do we make sure this is true?
There is widespread industry understanding and agreement, according to Pettingill, that engine oil viscosity corresponds with fuel consumption and that lower-viscosity engine oil facilitates higher fuel economy. There is a very strong industry consensus, so even in the case of FA-4 oils—which were launched at the same time as the most recent category of CK-4—there was no actual fuel economy test that you had to perform to demonstrate the FA-4 oils' fuel economy potential. As a result, in higher grades with higher HTHSs than in lower grades with lower HTHSs, you will use more fuel.
Acknowledge the Prototypes
Can we produce a heavy-duty engine oil that provides adequate engine protection while having a viscosity that is lower than SAE 30 and FA-4 standards? Pettingill said.
In response, Petro-Canada Lubricants developed two experimental 0W-20 heavy-duty diesel engine oil formulations and field-tested them. In North America, there are no 0W-20 heavy-duty engine oil formulations that are commercially accessible.
According to Pettingill, viscosity grade is based on kinematic viscosity at 100 degrees Celsius. The standard grades that you typically see are 10W-40, 15W-40, or 5W-40, which have a higher viscosity. The industry and OEM have just approved SAE 30 grade. We are testing even lower to provide improved fuel economy in the SAE 20 zone.
Can we produce a heavy-duty engine oil that provides adequate engine protection while having a viscosity that is lower than SAE 30 and FA-4 standards?
- John Pettingill, Petro-Canada Lubricants
But there are certain formulation challenges with low-viscosity engine oils. It's not that easy, Pettingill said. Without carefully analyzing what needs to be done to still protect the engine, you shouldn't blindly enter a test program or a field trial.
Petro-main Canada's formulation concerns were caused by the oils' low HTHS values, which would endanger the oil film strength needed to protect crucial engine components. It was also concerned about the base oil's low viscosity because it endangered the strength of the coating and might make it more volatile at high operating temperatures.
The use of tested performance additive technology, which is common to API CK-4 products, has, in part, decreased the threat, according to Pettingill. Because it was such a novel approach, the prototype 0W-20 oils were constantly monitored with regular samples and testing through our employed oil analysis technology to verify for critical performance characteristics during the fuel trial. The longevity of these oils needs to be confirmed.
Assessment and Results
Both 0W-20 prototype oils received test codes prior to testing in order to prevent potential bias. The oils were given the labels Test Oil Grey and Test Oil Beige. In addition to other formulation commonalities, the two distinct 0W-20 formulations shared the same base oil viscosity objectives and kinematic viscosities. The same group of additives and Group III base oils were used to make both oils.
The oils used a variety of viscosity modifiers. According to Pettingill, Test Oil Grey has a comb polymer while Test Oil Beige has a star polymer. What must fulfill the 0W-20 viscosity requirements' physical qualities are otherwise pretty comparable.
The testing conditions, in Pettingill's opinion, were difficult. He stated, "They were actually put to a harsh test. If they can survive under extremely trying conditions, then less loaded conditions shouldn't be a problem."
The Navistar MaxxForce N13 engines that were used in the tests were powering the ProStar International trucks. Long-distance routes with a maximum gross truck weight loading of 140,000 pounds were involved. This is a severe obligation, in Pettingill's opinion. Because of how much weight they are carrying, the vehicles "use a significant quantity of fuel, which really puts the oils to the test." Away from the Toronto metropolitan area, the testing location was in Ontario, Canada.
For context, Pettingill said, "The field testing data includes data from an API-licensed FA-4 10W-30 oil since you're not used to seeing data from 0W-20 oils." A code name was assigned to Test Oil Amber, the 10W-30 oil that served as the benchmark for the evaluation of Test Oils Grey and Beige. Test Oil Amber was largely created using Group II base oil.
The test methods used, according to Pettingill, were standard industry methods that are routinely found in used oil analysis reports. Among the test methods employed were ASTM D445 for kinematic viscosity at 100 °C, ASTM D2896 for total base number, ASTM D664 for total acid number, ASTM E2412 for oxidation, and ASTM D5185 for iron content.
The testing results were attained by examining used oil from duplicate runs of both test oils in similar trucks with similar duty cycles.
At the conclusion of the testing, the viscosity of Test Oil Beige exceeded the SAE 20-grade limits and entered the SAE 30 range. Test Oil Grey kept its intended viscosity during testing. According to Pettingill, this indicates that Test Oil Grey would maintain its fuel economy better than Test Oil Beige because it did not thicken into the higher grade.
While Test Oil Amber's total acid number increased more quickly than that of Test Oils Beige and Grey, Test Oils Grey and Beige both demonstrated superior total base number retention than Test Oil Amber.
Pettingill claims that neither base depletion nor acid increase happens quickly, which is fantastic for 0W-20 products. It's intriguing to watch this. Field tests frequently turn up information that you hadn't planned on finding. These 0W-20 test oils are produced utilizing superior Group III base oils, which most likely enhances the interaction between the additives and base oils in these products and is probably one of the key factors enabling these fantastic attributes.
Test Oils Beige and Grey demonstrated strong oxidation resistance, which is essential for keeping the oil's purity. Pettingill recommends a lower oxidation level. In terms of direction, Test Oil Amber is preferable to Test Oil Grey and Beige. This is simply one more encouraging sign of how well these 0W-20 oils are working. As a result of its resistance to oxidation, the oil maintains its integrity and the additive package keeps working.
The most significant finding is that we have demonstrated that reliable engine protection with a 0W-20 oil is possible through our own field tests, which were carried out at maximum, high loads.
- John Pettingill, Petro-Canada Lubricants
How long-lasting were the wear-resistance ratings of Test Oils Beige and Grey?
According to Pettingill, any oil in an engine will eventually develop wear metal accumulation. They rise as the drain interval gets longer. The industry would view 100 parts per million as a relatively conservative upper limit for the amount of iron present. According to some OEMs, you shouldn't be as conservative as you are, and they would allow a tighter restriction.
By the time the test run had covered 50,000 kilometers, all three test oils had successfully kept wear metals far below 100 ppm. Test Oil Grey was the best performer with the least quantity of iron metal accumulation. Out of the three oils, Test Oil Beige displayed the most metal accumulation.
The most crucial aspect, in Pettingill's opinion, is that our own field testing has shown that reliable engine protection with a 0W-20 oil is attainable under extreme, maximum loads.
