New oil specs for heavy-duty diesel engines

When the EPA set the deadline for manufacturers to come up with Tier 2 emissions compliant engines by October 1, 2002 – 14 months ahead of schedule – everyone knew there wouldn’t be enough time for lengthy field tests on the new engines.

What was known from lab tests was engines using exhaust gas recirculation (EGR) technology to reduce emissions ran hotter and generated more soot and acid than previous models. To handle these conditions and keep drain intervals at their earlier levels oil companies worked with manufacturers to develop a new oil spec for heavy-duty diesel engines, the American Petroleum

Institute CI-4 standard, which became official in December 2001.
Since the October 2002 engine deadline, however, manufacturers have amassed considerable field data on their new engines and many have decided to revise their specs on lube oils. “Oil performance specs are changing faster than ever,” says Dan Arcy, product-marketing manager, Shell Lubricants. “Since the API CI-4 category was finalized there have been five specs added.”

The changes have not been radical. According to Mark Betner, heavy-duty products manager for Citgo Petroleum, most of the premium oils from reputable companies were able to meet the new specs without changes to their formulations or have since reformulated. But if you are using an off-brand oil or even a low-grade formulation of oil from a well-known brand that does not meet the new specs you could be accelerating wear on your engine, hurting fuel economy and shortening your drain intervals. Now more than ever, it’s time to check and make sure the oil you’re using meets your engine manufacturer’s requirements for any engine sold since October 2002.

Field data show new needs
Mack Trucks announced its EO-N Premium Plus spec in the spring of 2002, before the engines hit the marketplace. After the new engines had racked up some highway time, Mack engineers noticed the soot tended to cause the oils to thicken and shear more quickly, says Greg Shank, a staff engineer for Mack-Volvo powertrains. (Shearing causes an oil to move out of its viscosity range.)

“The gear drives and the injection systems had changed and that created more shear than the older engines,” Shank says. So Mack asked for a more stringent test of shear stability and put out a new spec in April of last year dubbed EO-N Premium Plus 03.

“As with previous Mack specifications the EO-N Premium Plus 03 specification was aimed at identifying oils that provided extended drain capabilities in Mack engines beyond those provided by the current API CI-4 specification,” says Gary Parsons, ChevronTexaco Global Lubricants commercial automotive business unit manager, North America. In order to meet the new spec, most oils had to be reformulated to include a new dispersant system as well as modifications to the viscosity index modifier to improve shear stability, he says.

Also on the heels of the CI-4 category, Cummins introduced the CES 20078 specification to assure performance primarily in slider-follower equipped engines like the Cummins “B Series” engines installed in Dodge pickup trucks.

Caterpillar used its own proprietary ACERT technology (rather than EGR) to cut emissions in its engines, but found the ash used to beef up acid control in the CI-4 oils sometimes increased piston deposits in its engines. Piston deposits can result in bore polishing, which can lead to a loss of oil control and excessive oil consumption.

Cat issued its own lube oil spec, ECF-1 in June 2003, which required lower ash levels.

Field data has indicated that EGR equipped engines experience oil thickening due to high soot levels.

CI-4 PLUS, the latest spec
This month the API is expected to establish a new CI-4 PLUS oil spec, which will go further toward improving oxidation resistance, shear stability, acid neutralization and soot dispersancy. Oils meeting this specification will provide extended drain capabilities in new and older engines and be less likely to shear out of grade or thicken as they are loaded with soot, Parsons says. The CI-4 PLUS oils will also meet most of the manufacturer-specific specs and be backward compatible with other specifications and earlier generations of engines. Shank, who chairs the Engine Manufacturers Association lubes committee, says one of the goals of the CI-4 PLUS spec is to give fleet owners a single oil that will work in a variety of different brands of engines.

Betner recommends you not choose an oil just because it’s the best, or the least expensive oil that meets the spec. “There are different goals out there,” he says. Some people want to keep their trucks and equipment three to five years and then get rid of them. Some want to optimize their drain intervals and reduce labor costs. Ask your supplier to define what the performance differential is between different quality levels and different brands based on your maintenance and lifecycle goals.”

“If you want the whole enchilada in terms of performance, fuel economy, cold weather starting, engine life and drain optimization, ask your supplier about synthetic 5W-40 heavy-duty engine oil,” Betner says. “These oils cost more, but it’s just like buying anything that has greater return on value.” (For more on the pros and cons of synthetic oils see “Regular vs. extended drains in off-road trucks,” page 39, in the May 2004 issue of Equipment World.)

More changes coming
The continuing evolution of emission requirements for Tier 3 engines mean lube oils will likewise continue to change, Arcy says. “By 2007 everybody using EGR will have double the amount of exhaust gas recirculating through their engines,” he says. Engines will also have to be fitted with exhaust air particulate traps, and on-road diesel fuel sulfur levels will drop from 500 to 15 parts per million. And since sulfur is the primary contributor to engine acidity the oil formulations designed to fight high acid levels in 2002 engines may be poison for 2007 engines.

Engine manufacturers and oil companies are working on a new category of lube oils, which will be finalized in 2006, but for now is called Proposed Category 10, or PC-10. Until now, lubricant developers have been able to focus entirely on the performance of the engine oil in the engine. Starting in 2007 when exhaust after-treatment devices will be used to meet the more stringent emissions standards, the impact of the engine oil on the performance of after-treatment devices will be of concern, Parsons says. Certain performance additives used in engine oils contain compounds that have the potential to foul after-treatment devices. As a result, future engine oil development is focusing on the effectiveness of the oil in the engine and the potential impact on the exhaust after-treatment devices.

So stay tuned, and don’t forget to read the labels.