Part I: The new engine oils are here and low-sulfur diesel isn’t far behind
*Editor’s note: In Part II of this series we’ll take a closer look at the new Tier II-compliant on-road diesel engines, and in Part III we’ll profile a group of contractors who have already made their fleets compliant with Tier II emissions standards.
In 1996 the Environmental Protection Agency put into law a huge regulatory program to drastically cut emissions of particulate matter (aka soot or PM) and oxides of nitrogen (NOx), from both on-road and off-road diesel engines.
In the first six years of this program most of the engine changes were transparent to the end users. But the changes from this point forward are going to alter forever the engines you use, the oils and fuel you put in them and some of the important details about how you manage your equipment.
Contractors may find it somewhat hard to believe, but all of these prior changes have been, and most of the changes going forward will be, good for them – and that’s not even counting the clean-air benefit.
Here’s why: As emissions regulations got tighter in the late 1990s manufacturers responded with more efficient, electronically smarter engines. Double-digit gains in horsepower were achieved without sacrificing fuel economy or ballooning engine size. And in response to the more demanding engines – and with an eye for this year’s Tier II on-road engine requirements – the petroleum industry engineered two quantum leaps in the performance standards for engine oils.
New on-road engines almost here
On October 1, a big change takes place in the world of on-road diesel engines. That’s the deadline the EPA has set for Caterpillar, Cummins, Mack, Detroit Diesel and Volvo to have their on-road truck engines ready to meet Tier II emissions standards.
Most of the manufacturers are using some type of EGR (exhaust gas recirculation) technology to meet the tougher standards. Caterpillar is working on a different technology it calls ACERT or advanced combustion emissions reduction technology, for both on- and off-road engines.
EGR engines place more demands on engine oil. In response, the petroleum industry has developed a new standard for heavy-duty diesel engine oils called API CI-4. The API stands for the American Petroleum Institute and the CI-4 is the latest and toughest standard, surpassing the CH-4 standards that were put into place just a few years ago.
“All the changes in oil formulas over the past 20 years have been driven by emissions regulations,” says Matthew Ansari, heavy-duty/automotive manager for ChevronTexaco Global Lubricants. “Emissions regulations forced engine manufacturers to come up with tighter and more severe engines, and those engines require better lubricants.”
The increasingly rigorous standards for engine oils dovetailed nicely with the improvements in engine design, says Peter Van Benthuysen, technical support for Shell Lubricants. “Over the years engine manufacturers have done a much better job in terms of design and material,” Van Benthuysen says. “Consequently engines last a heck of a lot longer, and they have been able to accomplish that in part because the oils have gotten better. Today it’s not unusual for on-road diesel engines to go a million miles before an overhaul.”
Fighting soot, heat and acid
The main objective for the API CI-4 oil standards, however, was to meet the needs of EGR engines. “With EGR the biggest challenge is the increased acidity in the engine,” Ansari says. “EGR recirculates combustion products back into the combustion chamber increasing the liner and ring exposures, so the oil has to do a better job of fighting acidity.”
Increased soot or particulate matter in the combustion chamber is another factor. “The hopes were with EGR that you wouldn’t have to tradeoff the control of particulates to get lower NOx,” says Dan Larkin, commercial vehicle lubricant technical advisor, ExxonMobil. Previous attempts to reduce these emissions had enabled engineers to reduce one, but not the other. “The overall feeling was that there wasn’t going to be as much soot. In reality they are beginning to get some time in on these engines and the soot is still there. It may not be at the levels anticipated, but it’s still a bullet on the list of things for which CI-4 was needed.” Soot is particularly harmful if it’s allowed to coagulate and form deposits on internal engine surfaces or clog filters.
EGR engines also run hotter. “The charge air temperature is higher, so overall thermal loading throughout the engine goes downstream to the pistons, rings and cooling system,” Larkin says. “That points to a need for good high-temperature oxidation control. If you don’t have that when you oxidize oil, you thicken it. It becomes difficult to pump and more difficult to get through the filter because you create insoluble by-products within the oil.” Oxidation can also create gum or varnish type deposits on pistons and other internal surfaces, he says.
Out with the old, in with the new
While all the petroleum companies with products that meet the standards can officially label their oils API CI-4 after September 5, most of the major companies have already started meeting the standard. After September 5, it’s unlikely you’ll find any of the older API CH-4 oil being sold. Some small refineries may continue to sell bulk oil that doesn’t meet the spec, however, so it’s important that you check.
“In the United States you won’t find API CH-4 oils anymore,” Ansari says. “But in other parts of the world it may be a different story. You go to South America, Asia or Africa where it is feasible to keep old technology around and you might find CF-4 oils or CG-4 oils,” he says.
So what happens if you put old oil in a new EGR engine? “It’s not a disaster,” Van Benthuysen says, “but the manufacturer might not warrant the engine if you do that.”
The reverse situation, putting CI-4 oil in old equipment, whether on-road or off-road, is all positive.
“API service catagories are backward compatible,” Van Benthuysen says. “You’ll have improved lubrication, improved deposit control and better wear control. Off-road equipment owners are really the benefactors in all of this, because they don’t have EGR engines and yet the oil quality they will be buying has been upgraded,” he says.
The sources we talked to stop short of saying the CI-4 oils will extend the life of older or non-EGR engines, but they wouldn’t rule it out either. Most agree that with careful oil sampling using CI-4 oils in non-EGR engines may help extend some drain intervals.
Changing your oil sampling procedures
But drain intervals, as always, depend on oil sampling, and that’s one of the key areas where you need to pay attention with the changeover to new oils.
“I recommend you contact your lab and make sure they have a sample of the oil you are using on file in their catalog and that they’ve looked at the new formulation,” Larkin says. “Then as a backup, when you get the new oil in, you should take a sample right out of the drum or tank and send that in with their first batch of used oil samples. Even if the lab has this oil on file, if you send in a sample, you have your own reference to compare to all your future results. So if you have a question about what the lab is recommending you can pull your own sample. If there is some anomaly you can call the lab and double check to make sure the lab is in tune with the new formulations and their equipment is set to go with that.”
Another reason for brand-specific samples is that not all CI-4 oils are the same. The API requires manufacturers to meet certain performance standards, but it doesn’t tell them how to meet those standards. So different oil companies have different additive packages and blends they use to disperse soot, cut acids and reduce oxidation.
“A lot of the companies are changing their additive suppliers with the CI-4 changes, either for price, performance or availability,” Larkin says, “and it’s important that you get that oil sample because the additive profile you are using may be quite a bit different. Once the dust settles in September, everybody should have new material in the tanks and that would be a good time to take a sample of each different product you use in your fleet.”
Low-sulfur diesel
Sulfur causes a lot of the problems associated with diesel engine exhaust emissions. And steps are underway to reduce the amount of sulfur in both on-road and off-road diesel fuel.
On-highway diesel fuel will have a reduction in sulfur content from its current level of 500 parts per million to 15 ppm to take effect in mid-2006. The EPA is still working on its proposal for off-road diesel. Current regulations allow for off-road diesel fuel to contain up to 5,000 ppm of sulfur, although the typical levels are more like 2,500 ppm.
On-highway trucks have already been through a learning curve in adapting to low-sulfur fuel. “In general when you remove the sulfur compounds you remove the compounds that provide lubrication for pumps and injectors,” says Mitch Oliver, Conoco’s product quality manager for the Rockies. “So in the early ’90s we had the issue of fuel pumps and injectors experiencing accelerated wear because of the lubricity of the fuel,” he says.
That problem was solved soon enough with changes in pump design and with additives that restored fuel lubricity. The second problem involved seal leakage.
In the process of driving sulfur compounds out of diesel, another category of compounds called aromatics can be reduced. “If certain types of elastomers are old enough to have lost their elasticity and if the aromatics level of diesel fuel is reduced significantly, it is possible that seals such as O-rings may fail as they shrink and result in fuel leaks,” says Manuch Nikanjam of the Chevron Products Company’s Fuels Technology Team.
“Proper vehicle maintenance to ensure that O-ring seals are changed according to the recommended schedule can prevent this problem,” Nikanjam says. “And the problem does not repeat itself once the cracked seals are replaced.” To avoid the problem entirely, most manufacturers switched to seals that don’t need aromatics to remain tight.
Less sulfur better for everyone
Those two issues aside, low-sulfur diesel fuel offers several benefits in addition to cleaner air. “Generally, lower sulfur levels in fuel have a favorable effect on corrosion,” says John Medley, fuels issue advisor for ExxonMobil.
“This very low sulfur level is also expected to make life much easier for the EGR systems as it will reduce the formation of sulfuric acid,” says Mike Ingham, manager of state fuels regulations for Chevron Products Company. “Reduced acid formation is also expected to reduce corrosive wear in the engine and possibly permit longer lubricant drain intervals as well.”
“It’s a fuel that’s more thermally stable; it tends not to create deposits and burns a little cleaner,” Oliver says. In cold weather in northern tier states, however, lower sulfur diesel tends to form more paraffins, which can clog filters. If, or when, this happens, Oliver says, the solution will be to blend kerosene with the low-sulfur diesel or to use cold-flow additives.
A multi-fuel future?
The big “if” with low-sulfur diesel fuels is the question of whether the EPA will structure the phase-in so that contractors will be faced with two different types of on-road diesel fuel and/or two different types of off-road diesel fuel.
“It is reasonable to speculate that the emissions standards and fuel specifications for nonroad and on-highway applications will merge at some point in the future,” says Ingham. “We expect nonroad diesel fuel sulfur content to be capped at 15 ppm at some point in the future, at least for fuels consumed in agriculture and construction equipment, but the timing is uncertain.”
“What we know now,” Medley says, “is that the 2007 highway diesel rule contemplates that there will be two highway fuels potentially available, the new ultra-low-sulfur diesel (15 ppm) and the current low-sulfur diesel (500 ppm) for the period from mid-2006 to mid-2010.”
Whether or not this dual-fuel solution migrates down to off-road construction equipment will be covered in the non-road (Part 89) proposal the EPA is expected to announce in early 2003.
