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It’s been a busy four years for the makers of heavy-duty on-road diesel engines and no less so for the producers of lube oils for these engines. Both groups have been scrambling to meet the latest round of deadlines imposed by the Environmental Protection Agency, which kick in January 1.
All on-highway diesel truck engines manufacturered from that day forward will have to emit fewer emissions and these new engines will require a new lube oil.
The good news is that the operational impact of these regulations on contractors has been minimal for the most part. The new engines are more expensive, but they’ve also become better and more efficient. The only change contractors and fleet managers have to make is in their preventive maintenance and the type of lube oil they use.
CJ-4 is not a jeep
The official spec for this new oil is the American Petroleum Institute CJ-4 category. (The CJ-4 name has nothing to do with Chrysler’s ever-popular Jeep. It’s just the next extension of a series of API specs – from CH-4 to CI-4, then CI-4+ and now CJ-4.)
The new oils have lower levels of phosphorous, ash and sulfur – additives that, if used in the 2007 engines, would increase maintenance and lower the performance of the exhaust aftertreament devices (diesel particulate filters and diesel oxidation catalysts) these engines need to produce cleaner exhaust. The new oils also have higher oxidation stability (resistance to breakdown in high heat situations) and soot dispersant capabilities – two conditions that get more severe in the new engines.
“Ash can plug up the diesel particulate filter, and when it is plugged up for a period of time it can cause back pressure, which has a detrimental effect on the whole engine,” says Reginald Dias, director, commercial products, ConocoPhillips Lubricants, Conoco brand. “The high levels of phosphorous and sulfur could have a negative effect or deactivate the catalyst in an oxidation catalyst. These aftertreatment devices are supposed to be warranted for 150,000 miles, but when you have higher ash, phosphorous or sulfur levels, that warranty could be voided,” he says.
How much it will cost to clean a DPF or oxidation catalyst has not been clearly established yet. Dan Arcy, technical manager for Shell Lubricants, estimates it may run from $300 to $500, not including a half day or so of downtime. How much more frequently you would have to clean the aftertreatment is likewise uncertain. A likely scenario is that if you were getting 150,000 miles between cleanups with the CJ-4 oil at 1-percent ash and you put a 1.5- percent ash product like CI-4+ into your engine, you may only get to 100,000 miles before you need a cleanout.
Lowering emissions – increasing issues
Aside from the exhaust aftertreatment devices, the 2007 engines have several other characteristics – primarily high soot levels and high heat – that require additional changes to the oil formulas.
The new engines rely in varying degrees on exhaust gas recirculation technology to help reduce emissions. In an EGR engine a percentage of the exhaust gas is recirculated back into the combustion chamber. This serves to dampen the intensity of the combustion cycle by diluting the amount of oxygen in the intake air and lowers the level of emissions created during combustion. One side effect, however, is that it also increases the level of soot in the oil as burned hydrocarbons are force fed into the cylinders.
And soot, if not managed, quickly becomes a problem. “Excessive soot causes abrasive wear and soot agglomeration, which can cause filter plugging and high backpressure in the filters,” says John Shepard, commercial on-highway marketing specialist for Chevron. “Where you will see abrasive wear is in the cam and tappet followers, the cross heads and the adjusting screws.”
Problems with a history
Soot levels became an issue when the first EGR engines were introduced in 2002/2003. At that time the industry came up with the CI-4 specification to deal with soot, high temperatures and high acidity in those engines. But to reach the more stringent 2007 emissions targets, engines had to increase their levels of EGR, hence soot levels rose beyond what the 2002/2003 engines were producing and beyond what CI-4 and CI-4+ oils were capable of handling.
The new oils seem to be handling the additional soot levels well. “In our tests we didn’t see significant increases in the amounts of soot in the heavy-EGR (2007) engines,” says Arcy. “Some engines had higher levels than others, but we didn’t see them double. But that’s part of the specification, to handle high levels of soot.” Soot can also excessively thicken oil at high temperatures and affect cold weather performance, Arcy adds, both of which are solved with the new CJ-4 formulations.
The 2007 engines will also run hotter than earlier generations of EGR engines. Where they can, manufacturers have boosted their engines’ cooling capacities, but the API standard requires that the CJ-4 formulations be able to perform under worst-case scenarios for both heat and soot. “They have been beefed up with non-ash containing compounds to reach these new levels of performance,” Dias says. “They have better anti-oxidants, newer additives and better performing additives, not necessarily more additives.”
One issue that is less of a concern with the 2007 engines is acidity. The TBN (total base number of an oil, a measure of alkalinity) was raised significantly in the CI-4 and CI-4+ oils due to the rapid formation of acidic compounds in the first EGR engines. But sulfur was the primary source of that acidity, and starting in 2007 all on-highway diesel fuel will have a lower fuel sulfur levels – dropping from 500 ppm to 15 ppm. This effectively eliminated acidity as an issue, and the CJ-4 formulas have lowered their TBN numbers as a result.
Tough times call for tough oils
For contractors and fleet owners one of the benefits of all this lube oil reengineering is that they now have a better quality of oil to put in their on-highway trucks. “The CJ-4 oil has the highest level of performance we have known,” Dias says. “It is a superior quality oil compared to the CI-4 and CI-4+ in almost all categories.”
The proof began to emerge last year in the testing phase. Several lube oil producers noted a decline in engine wear while testing their CJ-4 formulas. “We are seeing up to a 38 percent reduction in wear on the pre-2007 engines we are testing,” Arcy says. The lower wear was evident in several areas of the engine, both corrosive and mechanical wear, but particularly evident was the reduction in iron wear, which is typically from areas such as cylinder liners, he says.
Arcy says their tests also showed lower levels of deposit formation in the cylinders, especially on piston rings. And keeping the rings cleaner longer will lead to less oil consumption.
Two lubes or one?
As the CJ-4 lubes come into the market for 2007 on-highway engines, contractors and fleet owners have to make a decision. Do you keep two different types of lube in inventory, one for the old engines and off-road equipment and one for the new on-highway trucks? Or do you keep things simple and go with just a single CJ-4 lube for all your needs?
The new lubes are going to cost more, anywhere from 7 to 15 percent more than the CI-4 or CI-4+ formulas. But, depending on the size of your fleet and how you service and maintain machines, you may also have additional costs in stocking, storing and keeping two different lubes in inventory or the complications of outfitting your lube trucks with two different types of oil. And with two lubes in the shop there is always the danger that an inexperienced technician may put the old lube in a new engine.
“Fleet owners need to make an economic analysis of the cost versus benefit,” Dias says. “The benefits of using a CJ-4 oil for all applications will probably override the other economic considerations and risk factors.”
What may nudge you toward the one-oil strategy is the fact that the CJ-4 oils are backward compatible with all your older trucks and equipment. Additionally, because it is a higher quality oil, the extra protection offered by CJ-4 formulas may prove to be worth the extra money.
“For some of your older equipment you will see improved soot handling and deposit control, which has the potential to add to the life of the vehicle,” Arcy says. “Putting CJ-4 in an older piece of equipment is going to provide some benefits, but if you make a mistake and put CI-4 or CI-4+ in a 2007 on-road engine you will eventually see an increase in your maintenance costs.” To prevent this you would need to immediately drain the crankcase and refill it with CJ-4 oil.
The only circumstance where the CJ-4 oil will not necessarily outperform older oils is when it’s used in an engine that burns high-sulfur diesel fuel. That’s not an issue for highway diesel fuel, since you won’t be able to get anything but 15 ppm sulfur diesel fuel starting January 1. But up until June 1, vendors of off-road diesel fuel will be able to sell product with up to 3,000 ppm sulfur. After June 1 off-road diesel fuel will drop to 500 ppm sulfur, and CJ-4 oil tested in engines burning 500 ppm fuel does fine. But with EGR engines running high sulfur fuel, acidity may raise its ugly head. “CJ-4 is formulated specifically to go with the new ultra-low-sulfur diesel fuel,” says Nicole Fujishige, Chevron commercial automotive marketing manager. “But it can be used in high-sulfur fuel applications. The risk is you may have to shorten your drain intervals.”
Oil analysis and drains
Regardless of what oil you use, rigorous oil analysis and a preventive maintenance program, as prescribed by your engine OEM and lube oil supplier, are always recommended. What has changed with CJ-4 is that you’ll probably be looking for different chemical signatures since the additive packages have changed. And since the TBN has been lowered, you’ll need to establish new baselines for that. The oil analysis services run by the major lube suppliers are in sync with the new values. But if you use an independent lab be sure they’re aware that you’re switching to a new lube oil.
Engine oil drain intervals will remain the same for CJ-4 oils as they were for CI-4 and CI-4+, says Shepard. Because of the higher quality of the CJ-4 oil, several manufacturers think oil drains may even be extended. At this point, it’s too early to tell, however, and lube oil companies say any recommendations about extended oil drain intervals must be first approved by the engine manufacturers.
“One question I get a lot about CJ-4 regards topping up,” Arcy says. “The answer is yes. If you have a pre-2007 engine and want to top up the oil with CJ-4, go ahead and do it. There are no compatibility problems. The two formulas will work together.”
Something you might also want to consider if you are going to switch to CJ-4 in a storage tank is to make sure you thoroughly clean out that tank, Arcy says. “It’s a great opportunity to pull the tank down to the bottom and clean it out,” he says. And, to avoid contaminating the new oil with the old, he says it’s best to have no more than 5 percent co-mingling.
One thing you do not want to do is burn waste oil by putting it in the fuel tank. “It only affects the 2007 engines,” Arcy says, “but the engine oil when it’s burned turns into ash which will plug the DPF rapidly.”
Although the CJ-4 oils are for the moment only needed for new on-highway and vocational trucks it’s likely that the spec will stay around for a while and may even become the standard for off-road engines by 2011.
“The on-road oil standards lead the effort,” Fujishige says. “We believe it will be the standard for the future. In 2011 there will be another reduction in the emissions allowed, and we hope that CJ-4 will meet those requirements. But until we do more testing on the on-road side we won’t know the answer.”