Fortunately, the major change to deal with the significant 2007 step has taken engine manufacturers through EPA2010 without the need for further lubricant tweaking. But we’re likely not done. There’s a possibility there’s more to come and again in response to a mandate by the EPA. This time it incorporates a push to lower greenhouse gases, particularly carbon dioxide. But you don’t get less CO2 unless you burn less fuel. So in reality, it’s less a mandate for emissions than for fuel economy improvement.
So there’s going to be a category change. Right now, there’s a committee of the American Petroleum Institute looking at just what this Proposed Category 11 will need for the engine manufacturers to meet the greenhouse gas emissions and fuel economy regulations that start to bite in 2014 and continue with increasing severity to 2018. The Engine Manufacturers’ Association is looking for this to be addressed in a category change in 2016. Originally the target date was January but in the most recent meeting, held October 2 this year, EMA asked if the date could be pushed back until April as some testing protocols had not been fully agreed in the taskforces.
One area to be addressed is that the lube oil is going to have to pump more easily and it’s likely the new Category will have to include viscosities such as 10W-30 and even 5W-30 in addition to the industry standard 15W-40 of today, said Dan Arcy, Chairman of API’s New Category Development Team and Shell’s Global OEM Technical Manager.
Arcy said that concerns about lower viscosities have dictated the Team’s proposal to look at a test for adhesive wear for the first time. “Previously we have looked at abrasive wear, as when soot particles get between sliding surfaces. But we want to make sure that, in the lighter viscosities, we don’t get metal-to-metal adhesion,” he said. This is where microscopic high spots can break through the oil film and microweld to each other.
“A couple of other changes have been proposed to PC11. New tests for oxygenation stability, for aeration to replace one that has been obsoleted, and an improved method for looking at shear stability,” Arcy said. “There was a proposal to incorporate a test for biodiesel but that is off the table for now, though it is still being watched.”
“Those are the performance benefits in addition to the incorporation of higher and lower viscosities to account for fuel economy,” Arcy concluded.
Viscosity change echoes the EPA’s Smartway recommendation, which talks of gains from a switch to a “low viscosity” oil of 0.5% in the summer and 2% in the winter.
Chevron’s Gary Parsons cautions that you have to be very circumspect when looking at the testing and results. In his company’s rigorous testing, presented at a number of recent lubricants conferences, his paper says that the reliable gains are in the order of 1% to 1.5% for a switch to 10W-30 and another 0.5% in going to a 5W-30.
So, economy is certainly a major factor being considered, but there are other technical reasons for the new oil category for diesels currently scheduled for the spring of 2016.
Steve Sturgess is a columnist for Diesel Progress and contributor to several trucking and transportation publications including NZ Truck & Driver and Diesel Magazine.