By Rolf Lockwood

The diesels that power your trucks are about to change. When North America’s six major engine makers reluctantly signed the so-called “consent decree” with the U.S. Environmental Protection Agency last October, they turned the corner-along with you-onto what could be a bumpy bit of road.

In order to meet tougher emissions standards by 2002, the medium- and heavy-duty diesel engines you buy will almost certainly need to have some sort of exhaust aftertreatment device on board, probably at some added expense. And in the meantime, the engines will demand different maintenance practices, especially with respect to oil.

Is it a horror story? No, at least not for 1999 engines. You likely won’t see any change in fuel economy, and some makers suggest you’ll actually do better with 1999 engines and those to come.
There is, however, a widely acknowledged challenge with engine lubrication. That’s because, in order to meet new 1999 emissions standards demanded by EPA, engine makers have had to retard injection timing-with the result that the injected fuel isn’t burned as completely as before.
With retarded timing, the piston has begun its downward stroke before combustion is done. A little fuel spills over the edge of the piston’s bowl, meets oil on the cylinder liner, and thus forms soot, which in turn gets scraped into the sump.

The downside to excessive soot includes plugged filters and early engine wear. One key question is this: does the lube oil you normally use have what it takes to handle increased soot buildup? Another is: what happens to your efforts to extend drain intervals?

The source of this apparent step backwards, in a nutshell, is the EPA’s claim that Caterpillar, Cummins, Detroit Diesel, Mack, Navistar International, and Volvo programmed their engines to meet federal emissions standards only in test mode-which mimicked urban freeway driving-and to defy the regulations by favoring fuel efficiency at highway speeds.

Although they insist they did nothing wrong, the companies agreed to pay individual fines adding up to nearly $84 million US in order to settle the allegations and avoid a protracted legal battle that would have cost a lot more in the long run. They also promised to reduce nitrous oxide (NOx) levels by roughly 50% for 1999 engines made after Jan. 1 this year.
And even tougher NOx limits-another 60% reduction over 1999 limits-were brought forward from 2004 to 2002.

Although engine makers dodged a full recall, the settlement requires them to offer rebuild kits to help lower NOx on engines made between 1993 and 1998, but only when they are brought in for major repairs. The broad result is that the engine companies have had to re-think their approach to balancing emissions control and fuel economy.

So far, they’ve risen to the challenge: in the past 20 years, engine manufacturers have cut regulated NOx emissions by almost 70% and lowered particulate emissions by 90%. And fuel economy has been improved by some 25%.

But the standards arising from the EPA deal will require relatively greater engineering gains in a compressed period of time.
The engine manufacturers won’t be able to reach these ambitious goals without the help of diligent maintenance managers and mechanics on a variety of issues, but especially when it comes to oil. Here are three questions both you and the engine makers face:

1. Will lubricants be able to handle the extra soot?
With the retarded timing of 1999 engines, and soot levels increased to 5% or 6% or more, the industry needed a new oil classification-even beyond the API CH-4 standard (also known as PC-7) that was already outmoded before its delayed introduction last December. Before that, unwilling to wait for CH-4, Mack and Cummins had developed their own more stringent oil specs.

Those two engine makers, incidentally, are increasingly becoming dominant in terms of classifying oils, so much so that the API effort to write an interim PC-7.5 spec was abandoned. The Mack/Cummins tests are tough enough that the oil industry itself has gone on to worry about the effects of the 2002 regulations, which will almost definitely demand some sort of exhaust-gas recirculation system on heavy-duty diesels.

The new Mack EO-M and Cummins CES 20071 tests advanced the oil art, and particularly its ability to keep soot in suspension, while staying with your typical CH-4 drain intervals. Cummins has since gone one better, further acknowledging the soot problem and working to ensure that long-term engine durability is not compromised. After the consent decree, it was quick to write a new lube oil spec, CES 20076, that increases the M11 crosshead wear test by 50%. This measures the abrasive effect of soot in the oil.

Mack did something similar. Oils meeting the new Mack EO-M Plus and Cummins CES 20076 standards have become known as CH-4+. Their advantages, compared to CG-4 oils, include better control of soot-induced wear, improved filter performance, better viscosity control, easier low-temperature pumping, increased valve-deck cleanliness, and improved oxidation control and inhibition.

If you’re using a mix of 1999 and earlier engines, it’s worth noting the different abilities of recent oils to handle soot. Straight CH-4 oil can manage a maximum soot content of 5%, while the immediately previous API classifications handle progressively less-CG-4 can manage 3% and CF-4 just 1.5%. The newest oils go to 7.5%.

2. What about extended oil-drain intervals?

Extending your oil-drain interval has always demanded a deliberate approach, one that changes according to the engine, the oil you use, and your operating environment. For example, excessive idling time can reduce the sensible interval by 50% or so, while sustained high road speeds can chop it by as much as 30%. The environmental perils of off-road work will have an obviously detrimental effect on your engine lube’s ability to last the distance.
Today’s engines are also different than their brethren of the recent past, in that they’re tighter, consume less oil (meaning less make-up oil to refresh the sump between changes), and have generally smaller lube capacity in the first place.

If you’ve got less oil to circulate, it stands to reason that it won’t handle an engine of the same capacity for quite as long. The relationship is a direct one: cut lube capacity by 10% and you chop your drain interval by 10% as well.
Every engine maker’s recommendations are different, and they vary so widely even within a given engine model range, that you absolutely must confer with them before deciding how to deal with drain intervals, especially now.

Mack’s EO-M lube standard is apparently good enough that the company has increased its 40,000-mile maximum recommended oil-change interval to 50,000 with new EO-M Plus engine oil.
To take advantage of the new 50,000-mile standard, however, Mack engineer Greg Shank says truck owners will have to adhere to a few key requirements:

–use EO-M Plus engine oil;
–ensure vehicles are used in sustained high-mileage, long-haul operations exceeding 100,000 miles per year;
–have a new E-Tech engine or an E7 engine with a V-Mac II electronic control system (1997 chassis or newer);
–have mileage of 6.0 mpg or better;
–and spec the Centri-Max oil filtration system and use the OEM’s centrifugal rotor.

Those are pretty specific conditions. Let’s take Cummins drain recommendations as another example. Cummins engineer Bill Stahl described the situation at a recent meeting of The Maintenance Council of the American Trucking Associations.
In normal duty (fuel economy between 5.5 and 6.5 mpg, in U.S. terms, and gross weights of 70,000 to 80,000 pounds), Stahl says a 1998 N14 Plus engine can go 22,500 miles between drains using an API CG-4 oil with an LF 3000 or LF 9009 filter. Use lube oil with a CH-4 or CES 20071 spec, and you might run 35,000 miles with an LF 9009 filter. But pour a CES 20076 oil in the sump and you’ll be way out at 45,000 miles, again presuming an LF 9009 filter.
That’s “normal” duty, remember. A common Canadian application would be called “severe” duty, meaning fuel economy less than 5.5 mpg and weights above 80,000 pounds. In that event, the CG-4 spec will get you 15,000-mile oil drains, CH-4 will deliver 22,500 miles, and even the very best oil-CES 20076-will only get you to the 27,500-mile mark.

But what happens with a 1999-spec N14 Plus engine? Shorter drains, that’s what. The maximum drain interval in normal duty is 10,000 miles less, at 35,000. And in severe service the oil is maxed out at 20,000 miles, not 27,500.

The lesson here is pretty straightforward. Chances are, pending confirmation from your engine maker, the diesels that you buy this year will come with different recommended oil-change intervals. Some will be shorter than you’re used to, but only if you’re accustomed to stretching to the maximum anyway. Many people don’t go beyond 15,000 miles, so for them there may be no change.

3) What can you do about it?

Unfortunately, “The new emissions standards and accompanying engine design changes will work against extending oil-drain intervals,” says Don Carver, legendary oil expert and program co-ordinator for Exxon’s Smartlube program.
But the process of optimizing drain intervals will remain the same.
First, profile your fleet. Come to know your engines, their oil capacity, typical idling time, operational severity, etc.

Then, estimate potential drain intervals and attached cost savings, balanced against the risk of stretching too far. And third, establish an oil-analysis regime for a small portion of the fleet. Test for three different intervals, and take oil samples every 3000 to 6000 miles so as to get a fix on wear rates and oil contamination.

A deliberate approach like that will see you through the next few years, but get ready for 2002. Yet another oil performance category-known as PC-9-is being developed right now for diesels equipped with the exhaust-gas recirculation devices that will be required in three years’ time. Those engines will also have soot loading due to retarded timing, but the EGR feature will increase corrosion, oxidation, and acidic contamination of the lube oil.

Given the history of engine makers and oil suppliers meeting increasingly demanding standards, there’s a great deal of faith that the engineers will continue to find ways to clear the bar. And that’s good news.
On the other hand, there’s an awful lot of expensive development work to be done. Somebody, somehow, is going to pay for that.