A Better Blend

| April 07, 2005

EGR engines allow exhaust to flow from the exhaust manifold through a heat exchanger full of engine coolant, and into the intake air stream. This reduces nitrogen-oxide emissions, but also puts more stress on the engine oil.

For truckers running emissions-friendly EGR (exhaust gas recirculation) engines, new CI-4 oils are required protection. And for those running earlier designs, the super oil could offer great news when it comes to maintenance intervals.

Recycled exhaust gases in the combustion chamber create a hostile environment inside the engines. And since the oil’s job is to protect the engine from its own internal evils, a more hostile environment means a need for better oil – hence the new API (American Petroleum Institute) CI-4 designation.

Using EGR technology, engines ingest not only intake air (which is normally only about 100 degrees Fahrenheit), but also 30 percent of their own exhaust at temperatures well above 200 degrees. As a result, the oil itself gets hotter even though the engine’s coolant does not.

According to Kevin Harrington, commercial vehicle lubricants product advisor at ExxonMobil, “EGR engines can be expected to run as much as 25 to 40 degrees hotter than non-EGR engines. This could cause premature oxidation in non-robust oil formulations.”
Acid is another concern. That’s because the exhaust gas that re-enters the engine contains components that, in the presence of water vapor, can form strong acids. Left unchecked, these acids can rapidly degrade oil and attack the metallic components of the engine.

Soot is still another factor. As Peter Thomson, global brand manager for the ChevronTexaco Delo product line says, “The oil must have better soot handling capacity to deal with increased soot loads to prevent excessive wear.”

While engines won’t actually generate any more soot (and exhaust particulate must not rise according to the Environmental Protection Agency standard), more soot may actually enter the oil. That’s because the exhaust in the cylinder will reduce the concentration of oxygen, and this can make it take longer for soot to burn off, allowing it to reach the cylinder liner and rings, and work its way down into the oil. If soot isn’t kept in suspension, it increases the viscosity of the oil, interfering with proper lubrication. High soot levels can also result in abrasive wear on rubbing parts like valve train rockers.

Just what’s better?
The new CI-4 lube is a perfect example of how the pressure of regulations results in significant technological developments. “The CI-4 specification has several significant performance upgrades that were needed to help ensure that the new exhaust gas recirculation diesel engines operate at maximum performance,” says Dan Arcy, products marketing manager for Shell Lubricants. “These upgrades include improved wear protection to better combat the harsher operating conditions that are sure to develop in EGR engines.

“[One] result is improved soot handling capability. The oil’s ability to resist oxidation
(high temperature) has also been increased. The alkaline reserve (TBN-“total base number”) or ability to neutralize acids was improved because EGR engines generate more acids. And the volatility of the oil was reduced to improve deposit control and oil consumption.”

The jug for Chevron Delo 400 will look very much the same. But when the jug lists the CI-4 designation on the label, you can be certain you’re getting engine oil that incorporates some impressive improvements in engine protection.

According to ChevronTexaco’s Thomson, the API CI-4 oil must have better thermal stability to deal with higher operating temperatures. Many oil formulators are now using highly refined base stocks and higher levels of oxidation inhibitor additive.

Harrington of ExxonMobil says, “Due to the stringent requirements of API CI-4, oils must be formulated with higher quality Group I and Group II base fluids, as well as more robust additive systems than their predecessors.”

The new oils are made with higher quality base stock. Group I base stocks are normally -refined, while Group II stocks are hydrocracked-a super refining process that removes impurities and makes the oil stable even when very hot. Group I base stocks are still used, however, because they dissolve deposits better, helping keep pistons clean. To make its CI-4 oils, ExxonMobil actually developed an improved way to add TBN, or acid resistance, while minimizing ash. It’s called “Trimer Core” technology.

These new CI-4 oils had to make it through an entire battery of difficult tests. The tests were tougher because the test standards were much higher than those used for old CH-4 requirements.

Market Forces
Harrington of ExxonMobil says, “It is unlikely that any major lubricant marketers will continue to include CH-4 quality heavy-duty engine oils in their U.S. product lines.” This is feasible as, “Oils that stand up to the rigors of API CI-4 [requirements] will automatically meet the requirements of previous API diesel engine service categories as well. Customers running mixed fleets comprised of EGR and non-EGR engines can use a single CI-4 oil for their entire fleet.”

Thomson of ChevronTexaco says, “Because CI-4 oils are mandatory in EGR engines and also provide higher levels of performance in other engines, most major lubricant suppliers have switched to offering this lubricant quality level.”

Arcy of Shell says, “The majority of lubricant marketers have qualified their premium products as API CI-4 or they are claiming API CI-4 performance. In the case of Shell Rotella T and Pennzoil Long Life, a running change was made in early 2002.”

You will need to check engine OEM requirements such as Mack EO-N Premium Plus and Cummins CES 20078 specifications. If you’re running a Cummins or Mack with EGR, you’ll need to make sure the oil meets the additional specification as not all CI-4 oils do.

There is a small possibility that there will actually still be some of the older quality CH-4 oils remaining in the marketplace due to the presence of Caterpillar’s developing ACERT technology to meet the lower-emissions requirements. But Harrington says, “Caterpillar is developing its own specification, to be known as CAT ECF-1, which will be added to the list of additional performance hurdles for CI-4 oils.”

Caterpillar’s Penny Shumaker, filter marketing consultant, says that, at this point, “The new CI-4 oil is not needed for Caterpillar engines because Cat does not use EGR.”

Whether the price of the new CI-4 oils will increase is debatable. “The market will determine the cost of CI-4 oils,” Arcy says. “However, it should be noted that tens of millions of dollars was invested on the development of the API CI-4 performance category and oil qualification.”

Thomson says so far, it does not appear that the introduction of API CI-4 has had much of an impact on the price levels of finished oils in the marketplace.

John Clevenger, manager of global product management at Fleetguard, says, “There is so much pricing pressure in the heavy-duty oil market that there can’t be an increase in price.”

Your Options
Because of the superb performance CI-4 is likely to give, those responsible for engine maintenance may feel compelled to make the switch now for your pre-EGR enignes.

“We feel that it makes more sense for fleets to purchase the API CI-4 products since these oils provide improved wear performance, better soot handling, better acid neutralization, and increased oxygen stability and volatility, all of which will benefit non-EGR engines,” Arcy says.

Thomson feels switching exclusively to CI-4 oils also could eliminate mistakes: “CI-4 oils are mandatory for use in EGR engines, and there is a chance for errors if multiple performance level oils are stocked,” he says. “We recommend fleets move immediately to an exclusively API CI-4 inventory. Given the current parity in pricing, the increased performance from API CI-4, and the fact that most lubricant suppliers have switched their products from API CH-4 to API CI-4, it doesn’t make much sense to purchase CH-4 oils.”

Harrington’s view is that CI-4 oils are fully backward compatible, and he thinks CH-4 is likely to disappear from the range of products marketed by the majors anyway.

Added Benefits
Harrington says users of CI-4 oils may see the following benefits in their engines: outstanding oil consumption control, fewer deposits and less wear caused by soot loading and improved wear performance, leading to longer drain and overhaul intervals.

“Engine builders have nominally designed their EGR engines to maintain the same drain intervals as non-EGR engines,” Thomson says. “However, actual field experience with EGR engines and API CI-4 oils is limited. Used oil analysis remains an important tool for determining which intervals are best for changing oil. This will be especially important while gaining experience.”

In EGR engines, drain intervals will most likely be shortened or, at best, remain the same. “A fleet needs to evaluate its maintenance intervals to see if it is a candidate for extended service,” Shell’s Arcy says. “A fleet accustomed to extending service intervals with non-EGR engines may have to adjust their drain intervals for their vehicles that have EGR engines.”

Indications are the future could be very bright for pre-EGR diesels that are in sound condition.

“We highly recommend that a fleet use an API CI-4 oil, mainly because the improvements in the oil quality have been proven to benefit non-EGR engines,” Arcy says. “In non-EGR engines, it may be possible to extend the service interval. However the fleet needs to evaluate the drain intervals based on its operating conditions.”

The benefit will be a cost savings for truck owners. “If drain intervals are extended with the API CI-4 oils, the maintenance costs will be reduced,” Thomson says.

“There might even be a push for 100,000-mile change intervals on pre-EGR engines,” says Fleetguards’s Clevenger. “In any case, you’re likely to see a lot of movement, including fleets keeping older equipment longer.”


A good oil filter must pass many stringent tests. Using the OE brand guarantees a filter that will protect your engine and keep your warranty in effect, and Caterpillar recommends only their branded filter. But, you should be able to buy an equivalent filter from another major supplier. Get approval from your dealer or a guarantee from the filter manufacturer to protect yourself.

Filtering through the Choices
What you see is not always what you get in an oil filter

When you buy an oil filter, you want to make sure it will not only protect your engine from wear, but does so well enough to keep any warranty that may apply in force. This is a situation you need to manage.

The problem, as expressed by Greg Shenk, senior staff engineer with the Mack/Volvo powertrain unit, is, “There’s no policeman out there. The danger is the will-fit guys who will just measure the thread size on the engine fitting and use a similar housing. The fact is, cheap might fit, but not work.”

“Using a quality filter is becoming more critical. The ’02 engines produce more contamination. We have to get it out of the engine in every way we can.”

Micron ratings need to be evaluated carefully. While there are good tests, Shenk maintains this is a risky area. “They might give you a micron rating. That can be a dangerous thing. Unfortunately, they can say it’s a 20-micron filter when it only takes out 50 percent of particles that size.”

Penny Shumaker, filter marketing consultant at Caterpillar, agrees: “Although the Multipass test for micron ratings is a good comparative test, a filter should be judged on field performance, quality and consistency, not ‘micron ratings,’ as these numbers can be misleading or easily abused.”

Micron ratings are expressed in terms of “nominal” and “absolute” standards. John Clevenger, manager of global product management at Fleetguard explains just how complex micron ratings actually are and how some manufacturers might be able to disguise actual performance. “You need to know the percentage of the size particle the filter actually removes,” he says. “The industry absolute standard means the filter must be able to remove 98.7 percent or more of the particles at the stated micron size – say 10-microns.” On top of that, for a heavy-duty truck engine filter, “The test must be done at a heavy-duty flow rate, typically gallons per minute.” Obviously, a filter not tested to the absolute standard or at the proper flow rate will under-perform on the engine even if it removes a significant percentage of particles of a given size under some conditions.

And, what happens if the filter isn’t good enough? Says Clevenger, “If you don’t have the right quality filters, you won’t have something blow up. The problem shows up in upper engine component wear first – the valve bridges and rockers – and not typically until 300,000 miles. Most people would never make the connection.”

The Right Filter
There are a couple of good starting points in the search for just the right oil filter. Of course, you can buy the OE filter. Amazingly, this is not always simply a matter of buying the engine manufacturer’s branded design. Clevenger says the OE product “is always private branded.” This means a filter manufacturer, not the engine manufacturer, actually makes it. Talk to your filter manufacturer and the engine OEM. You may find that your filter manufacturer actually makes the OE filter. This means that the filter they make that is specified for your engine application is likely to be identical.

The third possibility is to “Ask the engine OEM for filtration performance specifications,” such as “particle efficiency.” Why might such standards be worth reviewing? He says one example is gaskets: “As oil performance requirements have increased, oils have gotten more aggressive toward gasket materials. The less expensive materials are prone to failure.” In other words, leaks on the road. In any event, with all the specifications, you could compare the details with specifications provided by your filter manufacturer, and find one that passes all the tests. Unfortunately, he points out, “Not every OEM may want to share this information.”

In this event, there is a simpler way of approaching the problem. Clevenger says, “You get what you pay for. If you buy a reputable brand, you’ll be OK.”

What’s the difference between a good filter and a not-so-good one? His view of the situation is that “All the major manufacturers in the U.S. get their media and components from the same sources.” So, media of the same basic type may not be any different. The biggest differences often come in terms of filter design. For example, putting more media into the filter means a higher particle efficiency because the oil flows more slowly through each square inch of the filtration medium, whatever it is. Clevenger says not to be too afraid of paying a reasonable price, or putting up with a price increase when the design changes. “The filter manufacturers know you can’t afford to gouge people.”

Shenk says with Mack’s OE filters, “We try to protect our OE filter for a short grace period after introduction. Then, I make the specifications available to the major filter companies. What you need is for them to put it on the filter can that the filter meets Mack spec’s. Or, you need them to certify in writing that their filter meets our spec’s.”
If you have certification, “Then, if we see filter-related wear in an engine, we challenge the filter manufacturer,” he adds.

Thus, a good starting point might be talking to your manufacturer’s representative to see if he has been in touch with the engine maker and knows their spec’s. This indicates a good faith effort to produce a filter that will satisfy factory requirements.

Shenk says that in Macks’ case, the company’s service bulletins also list the specifications. You might be able to compare those with detailed manufacturers spec’s, as Clevenger also suggested. Such spec’s would include, for example, not only the efficiency of the filter in terms of what it removes, but its capacity to hold enough total material. In any event, Shenk agrees with Clevenger that, “The key is to stick with the major, reputable heavy duty filter manufacturers.” That’s good protection if you can’t get a written guarantee or review printed spec’s.

Caterpillar’s Shumaker says, “Assuming the customer has not entered into a Customer Support Agreement with his dealer, the warranty is not dependent upon the use of OEM parts.” She goes on to say that, although Caterpillar recommends the use of Caterpillar branded filters and does not formally list any others, you should talk to your dealer to find out about filters that will maintain your warranty and protect your engine. Getting approval for the brand you are buying is always helpful.

There’s one additional concern if you are running extended change intervals. The media must be designed to stand up as long as the filter is on the engine. This sometimes means a change in the type of media. Clevenger says, “Paper may turn to mush. Resin binders that hold the paper in position may fail.” Use a filter specifically designed for the interval you are running no matter how long it is.


The EGR Principle

In the comic strip L’il Abner, Gen. Bullmoose invented a car that would run on smog. In real life, most truck engine makers use exhaust gas recirculation, which is the opposite of Bullmoose’s idea. EGR is a way to dampen the fire in a diesel cylinder. The exhaust that’s put back in absorbs heat so less nitrogen and oxygen will combine and form polluting nitrogen-oxides (NOx). EGR cuts NOx to half the prior allowable level.

The turbochargers on the new Cummins, Detroit Diesel, and Mack engines have variable geometry-a way to boost back pressure in the exhaust manifold, forcing exhaust into the intake manifold even though it’s already pressurized by the turbo’s compressor. The exhaust takes a different path from the engine’s intake air, passing through a jacket water exhaust gas cooler rather than the charge air cooler. The exhaust cooler uses only jacket water at 180 degrees and up. This is done to keep water and acids that are in the exhaust from cooling and turning into a liquid. This will minimize their impact on the engine.

Volvo, too, uses an EGR system with jacket-water-cooling. But, the Volvo V-Pulse system develops the pressure necessary to force exhaust to recirculate using the pressure pulses in the exhaust manifold.

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