Just three years along with the current CK-4 FA-4 oils, and with market penetration still in single digits, engineers at Petro-Canada Lubricants already have super-low viscosity 0W-20 and 5W-20 engine oils in test trucks. It's all part of the push for greater fuel economy, according to Product Specialist John Pettingill.

"To realize even better fuel economy benefits, you'd need to lower the High Temperature High Shear [HTHS] limit to somewhere below 2.9 centipoise [cP – a measure of viscosity]," said Pettingill, during a media briefing in Toronto at a Honda Toronto Indy event.

"If we can demonstrate that we can make a 0W-20 oil that can protect as well as a 10W-30 or a 15W-40 and still provide the fuel economy benefits,” he continued, “that would be a real step forward in the future of engine oils."

Thinner, low-viscosity oils have better flow properties, particularly in cold temperatures, but generally are easier to pump through the engine. That induces less parasitic drag, which lightens the load on the engine and lowers fuel consumption.

While the CK-4 and FA-4 oils are thinnest ever used in heavy duty diesel engine, engineers are already asking how low can we go and what's the point in going lower?

"Twenty-grade oils are passenger-car territory," Pettingill said. "this is all very exciting because we’re talking heavy-duty here."

Asked about the need for thinner oils going forward, he said that while there's no specific proposed category on the table at this time, he saw a reference to "PC12" in an email just a few weeks ago.

"The previous category, CJ-4, lasted about 10 years, and we're now about three years into the current category," he said. "CK-4 and FA-4 started in December 2016 and they are hoping to get another 10 years from that one. It takes about 5 years to really get something going, so 5 years from 2016 would put us in 2021. That's when we'll start thinking about what the fleets' and OEMs' needs might be going forward."

Most of the category changes are the result of emissions restrictions. In addition to the main measurables, particulate matter and oxides of nitrogen, there's CO2 now as well. "We can only confront carbon dioxide through improvements in fuel economy and oil will have a role to play there," Pettingill observed.

If the category timeframe seems a little compressed, it's just perception. Adoption rates for the current standard are low, which leaves some with the impression that it's still a "new" standard. Some vehicle owners are still awaiting approval from some OEMs, while other fleets, reluctant to carry a mix of products in parts inventory, have decided to stick with CJ-4 oils for the time being.

And 40-grade oils are still a big part of the market. All oil marketers still have 15W-40 offerings because it's 60-70% of the market, depending on the region, Pettingill said.

"There's still a lot of volume in the 15W-40 space, but that is shifting to 10W-30, primarily the CK-4,” he said. “There's really no longer any need for CJ-4 now that we have CK-4 with much better performance as well as backward-compatibility. The CK-4 is clearly a better product."

There's much more to improving fuel economy than relying just on engine oil. Improvement can also come from lighter-viscosity fluids, but that will have to be accomplished without sacrificing engine reliability.

“That's why we have this oil in real-world trucks right now," said Petro-Canada Lubricants' category manager for heavy-duty engine and driveline oils, Barnaby Ngai. "We are trialing this product and we plan to provide updates on the progress as we accumulate more mileage in the test.

"Future engine designs will likely require lighter-viscosity fluids, but there are no such engines out there now to test with, so it's a bit of a chicken-and- egg thing," he added.