Lower viscosity, PC-11 and oil’s role in fuel economy

Dan Arcy, global OEM technical manager for Shell, gave international journalists, including those from Europe (which will soon be switching to Euro 6 emissions standards, which are very similar to U.S. EPA 2010) and Asia a behind-the-scenes peek into the thought processes of the task force responsible for developing PC-11 (proposed category 11) oils during a briefing at Shell’s Technology Centre in Hamburg, Germand.

According to Arcy, there are a lot of organizations worldwide that define oil specifications, although API in the US, ACEA in Europe and JASO in Japan are the three primary drivers.

(To read about PC-11, click here)

In the U.S., as most now know, API is working on a new oil category, currently called PC-11. “A lot of what changes these specifications is emissions,” Arcy said. “There are different emissions standards going into effect all over the world.”

The need for PC-11 in the U.S. is being driven by a number of factors, all related to the greenhouse gas emissions regulations being phased in between 2014 and 2017.

“When this category was requested (by manufacturers), the real driver was to meet lower CO2 emissions…and improve fuel economy,” Arcy said.

Other factors also include the increased use of biofuels (the old CJ-4 category did not include a test for biofuels), and newer equipment that is making older components that the CJ-4 test was developed on obsolete.

By the time the first licensing for PC-11 is allowed, in January 2016, it will have been 10 years since the introduction of CJ-4.

“The reason that’s significant is, historically, we’ve had new categories every 4-5 years,” Arcy said. “So it really is a testament to the durability and development [of CJ-4).”

Arcy said the manufacturers have asked for the PC-11 category to meet higher oxidation stability, shear stability, and scuffing and adhesive wear as well as improved aeration benefits.

“Air is not a real good lubricant, so they wanted to get the air out of oil,” Arcy said.

The new category will include two subcategories, one to maintain historical heavy duty criteria, ie. higher viscosity grades such as 15W-30, and one to provide lower viscosity and improve fuel economy while maintaining durability. Importantly, Arcy said, there will be no specific test for fuel economy.

“By going thinner in viscosity, we can get better fuel economy,” he said. “[but] there is no actual fuel economy test that is part of this proposed category although the benefit is improved fuel economy.”

Arcy said there will be 11 tests for oils to meet the new category, seven “holdover” tests from the CJ-4 category and four new tests.

One of the major milestones is the announcement of which oxidation test will be used. The oxidation taskforce has been looking at a number of possibilities and is expected to announce the test that will be used on Oct. 2, Arcy said.

The reasons OEMs are pushing for lower viscosity oils is fairly obvious, according to Keith Selby, global technology manager, heavy duty oils.

During his presentation, Selby noted four separate fuel economy tests, including three in the U.S., that prove the fuel economy value of lower-viscosity oil. A test of Class 7 Penske vehicles showed a 1.6% mpg benefit using a 10W-30 oil vs. a 15W-40. A similar test with a Class 7 medium-duty delivery truck in urban use found a 3.3% mpg improvement and a Schneider National test resulted in 1.57% improvement.

Over in Europe, a nine-month test with an English grocery delivery company using a tractor running a Euro 5 engine and trailer not only found a 2% fuel economy improvement, but also no additional component wear.

“It shows that you can use lower viscosity oils without added wear,” Selby said.