EGR Diesel Engines And The Oils They Use... Part One

By BRETT WINBERG & DEBORAH LOCKRIDGE (Heavy Duty Trucking)

Most everyone reading this week’s newsletter understands what EGR stands for. EGR (Exhaust Gas Recirculation) systems have been used since October 2002 by five major diesel engine manufacturers (Cummins, Detroit Diesel, International, Mack and Volvo) to reduce emissions of smog-producing nitrogen oxides (NOx) from diesel truck engines. Depending on engine operating conditions, these systems divert from 5 to 30 percent of an engine’s exhaust stream through an air-to-water cooler, then back into the combustion chambers, where the cooled gases reduce peak temperatures and, thus, retard NOx formation.

As we all know, concerns about EGR engines running hotter and potentially dumping more acid and soot into the engine’s lubricating oil prompted the development of a new heavy-duty oil, designated CI-4 by the American Petroleum Institute (API). By all accounts, the new oil is doing a good job, and many truck owners are tempted to use the same extended drain intervals established for the previous oil, CH-4. While some people in the industry say that’s probably okay to do, others advise caution. The best advice is to follow the manufacturer’s recommendations until a cautious oil-analysis program, involving input from both the engine manufacturer and oil manufacture to assure no damage is being done to the engine and it components.

In fact, two years ago, there were concerns that Oct. '02 EGR engines would require oil that would be so different from previous oils that it would not work in older engines. As recently as last summer, there were some in the industry predicting that the new oils, dubbed CI-4 by the American Petroleum Institute's licensing program, would be much more expensive than the CH-4 oils they replaced.

      "Most of the major lubricant suppliers reformulated or introduced heavy duty motor oils meeting API CI-4 well in advance of the actual September 2002 date in which products could be officially API licensed," says Gary Parsons, global consumer and transport segment director at ChevronTexaco. Chevron Delo 400 Multigrade, he says, has met the CI-4 requirements since 1998.

Because the CI-4 oils are backwards compatible with older engines, most manufacturers are no longer offering oils that meet only the CH-4 category and not the CI-4 rating. Oil companies and fleets typically said they didn't want the hassle of dealing with two different oils, and the new oils promise to be better for both old and new engines in the fleet.

Dan Arcy, product manager for heavy-duty lubricants at Shell, offers an example of benefits offered by the new oil category. The CI-4 test for volatility, basically the amount of oil burned off at high temperature, allows no more than 15%. For the previous standard, CH-4, that number was 18% .

      "What that means to the consumer is their oil consumption rate, and more importantly the potential for deposit formulation, is far less than what it used to be. So they're going to end up using less oil."

The only cautionary note we heard from the oil makers was from Castrol, which says some CI-4 oils use a relatively high sulfated ash content, which has been shown to generate piston deposits.

As for the cost increase… those concerns appear to have been overblown as well. There have been some increases in oil prices, but it's difficult to tell how much of that has been due to market conditions such as higher prices for raw materials, and how much has been from passing along the cost of development of new formulations.

      "There was a lot of money put into developing these oils," says Shell's Arcy, "but the market always drives the price. When it comes down to it, the difference in cost is minimal."

That's the good news on CI-4 oils. The bad news is, even with these better oils, the new EGR engines could put a crimp in extended oil drain programs.

Extended oil drain intervals are one of the most common ways to save money on lubricants and oil changes. Not only can you save on the cost of oil, but also more importantly, you save the cost of filter and labor for oil changes, and keep the truck on the road making money. "You can pay your oil bill many times over with extended oil drains," says Mark Betner, heavy-duty product manager at CITGO.

However, the jury is still out on how long you'll be able to extend oil drains with EGR engines. Most engine and oil manufacturers are advising caution.

      "The chances of doing extended drains with EGR engines is minimal," says Shell's Arcy. "It's not something you're going to want to do, as they are generating more acids and a lot more soot."

Others, however, are more optimistic.

      "While the new EGR engines are expected to lower drain intervals in some circumstances, fleets may still be able to safely extend drains by carefully monitoring the oil," says Karen Campbell, Castrol spokesperson.

CITGO's Mark Betner says the general consensus at a recent meeting of the Technology and Maintenance Council was that most fleets are not currently extending drain intervals to the point where it would be a problem. "The data is just beginning to roll in," Betner says, "but we felt that if you were under 35,000 miles you probably wouldn't have to roll your drain interval back."

The one thing everyone agrees on is that because there is limited real-world fleet experience with EGR engines, used oil analysis is vital to determine the right drains intervals for your equipment and operating conditions.

ChevronTexaco's Parsons recommends that wear metals, viscosity, TBN, and soot levels be used as indicators of when the oil has served its useful life. Check with your engine manufacturer about recommended drain intervals and how exceeding them might affect your warranty. Parsons also recommends using high quality full flow/bypass engine oil filters to help filter out impurities.

Next week we'll follow up with Part Two of this series... can you choose these new oils based on price alone? Furthermore, do these premium oils all meet the new CI-4 test requirements? Tune into your Inbox next Monday to find out.

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