An Expert Talks Diesel Engine Oil
Aug 1, 2019—Last week, NOLN, a sister publication of Ratchet+Wrench, spent some time at the 37th-annual SuperRigs event put on by Shell Rotella.
The truck show and contest features working big rigs and took place in Albert Lea, Minn.
NOLN also got a chance to sit down with Dan Arcy, global OEM technical manager for Shell. Arcy was also chairman of the New Category Development Team through the American Petroleum Industry. That team led the effort to develop the newest diesel engine service categories: API CK-4 and FA-4.
Oil brands could begin licensing CK-4 and FA-4 diesel engine oils starting in late 2016. CK-4 is the continuation of the previous service category, CJ-4. And it’s backwards compatible, meaning that oils certified to the new standard will work with engines that require a previous standard.
Just like with the gasoline engine oil, diesel engine oil standards are changing to reflect a trend toward greater fuel efficiency. Lower oil viscosity has been a way to aid that effort.
“The engine manufacturers are looking to move toward lower viscosity grades,” Arcy said. “The reason for that is that lower viscosity grades can provide fuel economy benefit. And fuel economy is where we get our CO2 reductions.”
FA-4 was developed for even lower viscosities to be used mainly in newer heavy duty on-highway trucks. One exception is that Ford chose those oils for its smaller diesel engines. What’s important to know is that, unlike CK-4, FA-4 oils are not backwards compatible for engines that require a previous API service category.
Arcy said that the new CK-4 oils must be able to perform better with those fuel-saving, lower viscosity levels. Otherwise, drivers wouldn’t put them in their vehicles.
“That’s one of the biggest questions that we have from our customers,” he said. “They’re not going to accept a reduction in durability of that engine just to get a little bit better fuel economy.”
The Ford Exception
After the release of CK-4 and FA-4 standards, Ford didn’t like what it was seeing in tests with the 6.7-liter diesel engine.
The company announced that it wouldn’t recommend the new service categories for any of its diesel engines. That is, unless the oil is also certified by its own standard that the company developed.
“The reason Ford came out with that is they said that the unique design of these engines actually puts a lot of stress on the oil,” Arcy said. “And they wanted to make sure that oils in the marketplace were oils that would meet the requirements.”
That standard, MTC171 F1, gave oil manufacturers another target for product development, but many, like Shell Rotella, rose to the challenge.
A list of oils that meet that Ford spec can be found here.
Diesel oil changes are a small part of a typical quick lube’s operation. According to the 2018 Operator Survey, just 5 percent of oil changes are performed on diesel engines.
But in case you hear that diesel noise pulling up to your bay, Arcy said that he recommends keeping a few grades on hand.
He said that 15W-40 is the predominant grade, and it’s most likely what customers will ask for if they know what diesel engines have been running for years.
But, as the trends dictate, lower viscosity grades are becoming more popular.
“5W-40 for sure,” Arcy said. “All three of your engine manufacturers for diesel pickups all recommend 5W-40s actually for year-round. But they recommend them specifically in the wintertime for cold weather pumpability.”
He added that 10W-30 is the primary grade for the 6.7-liter Ford engines, but the products that meet the Ford spec come in all kinds of grades.
As always, double check the OEM recommendations.