Lower viscosity oils could help improve engine performance and durability. By Jack Hunsley
A well-oiled machine can significantly benefit efficiency, reliability, and productivity. The internal combustion engine (ICE) is no exception and effective lubrication remains a key talking point for automotive players. However, the challenges and opportunities in this segment are changing.
Lower viscosity
Speaking with Automotive World, Greg Matheson, Commercial Product Manager at chemicals expert Lubrizol, says that many fleet owners are now asking questions around lower viscosity oils, partially due to the arrival of smaller engine configurations across the vehicle spectrum.
For instance, as Matheson notes in the context of heavy-duty vehicles, though engine sizes of 15- or 16-litres were prevalent five to ten years ago the segment is now moving towards smaller configurations to try and improve mechanical proficiency. In the context of lubricants, this transition means that oils will be expected to operate in engines with tighter clearances while providing on par or better overall performance and will thus need to be able to move effectively through smaller spaces.
“One of the big questions being debated right now is just how big of a step-change we could get in terms of fuel efficiency,” said Matheson. “There’s definitely room where we could continue to optimise and improve heavy-duty engine oils for ICE vehicles.”
Lower viscosity lubricants could also lead to improved fuel economy savings, with Matheson stating that both the current leading API CK-4 and FA-4 specification oils can “bring pretty substantial fuel efficiency numbers.” Looking down the viscosity scale, he says, a CK-4 oil around the 15W-40 or 5- or 10W-30 grade mark can yield fuel economy improvements of 0.5-1.5%. Dropping even further into FA-4 oils can bring an additional 0.4-0.7% improvement.
Successful integration should also enable similar, if not better, in-engine performance than current oils. For instance, Lubrizol says that lower viscosity lubricants are particularly adept at dealing with increased piston temperatures which are used to improve engine combustion. One scenario sees pistons squirted with oil through narrow passages which, if designed with low viscosity oil in mind, can create a more effective cooling system.
Durability also stands to gain. As Matheson detailed, a key concern for many of Lubrizol’s customers is whether CK-4 and FA-4 oils can at least match current products. “When you look at the way the API performance category is structured, whether the oil is at a CK-4 level performance or an FA-4, it’s passing the same test and in some cases, the OEMs have even more stringent requirements,” he said. “Those oils are protecting the engine the same way and, quite frankly, as you move to FA-4 you could argue that you’re getting enhanced levels of protection.”
Lubricant usage in aftertreatment systems is another focus area, with the industry asking questions such as: how will new technology impact current aftertreatment systems, and how could new lubricants provide added protection against catalyst poisoning or particulate filter blocking? “Those benefits,” Matheson said, “could potentially help further reduce the NOx levels being emitted from these engines.”
Alternative powertrain solutions are clearly going to have a future, but it is challenging to say where that cut off point will be
Other considerations include how to improve key performance criteria such as enhanced oxidation control in the engine. This could extend the intervals between oil drains, thus minimising downtimeand corrosion and wear protection. “That’s going to maintain what’s already a very robust and efficient performance category in API CK-4 and FA-4,” Matheson detailed. “That’s something in the North American industry that’s being looked at right now and there are many ongoing discussions.”
Time yet to improve
Though many years out, the lubricant sector is already preparing for upcoming powertrain tech. For the heavy-duty space, one consideration is the potential use of hydrogen in ICEs. Matheson says that this is an area that Lubrizol, its competitors and oil marketers are continuing to explore, but that the priority remains largely on squeezing further performance out of existing and more near-term technologies.
“Alternative powertrain solutions are clearly going to have a future, but it is challenging to say where that cut off point will be,” said Matheson. “Even though the OEMs are making big investments they’re also looking at how they can continue to optimise diesel ICEs.”
Industry bodies are of a similar opinion, as underlined by the Engine Manufacturer Association’s (EMA’s) recent request in North America for the lubricant industry to assess a new performance category. “That’s a clear indication that diesel ICE engines still have a future,” said Matheson. “The fact that we’re looking at how we can optimise lubricants to bring even more efficiency and benefits to the market is a sign that diesel engines will probably be prevalent for the next several decades.”