For instance, take the plunger out of a fuel injector from one of today's diesel engines and hold it in your hand. The warmth of your hand will make the metal expand so you can't get the plunger back inside the barrel.
That's according to Paul Bandoly, manager of technical service and customer training at Wix Filters, as he explains just how tight the tolerances are in today's high-pressure fuel injection systems. That means the cleanliness of the fuel going through those tiny openings is more important than ever.
At the same time, many fleets are interested in extending their oil drain intervals, with the help of used-oil analysis - but that puts additional demands on oil filters and may require beefed-up fuel filters as well.
The right filter
The independent distributor's expertise in parts comes into play to make sure truck owners are buying the right filters for their equipment, and that they get a quality product.
"I'm not saying the brand names are the best, but I've seen city fleets buy aftermarket filters that were so cheap, when they had issues, they'd find out they had collapsed," says Mike Dobbs, operations and service manager at the Waco, Texas, branch of WheelTime Network member Stewart & Stevenson.
You can't tell if a filter's the right one simply by appearance. Two filters could use the same can and the same gasket; you could cut it apart and the media looks the same to the naked eye. But the structure of the media and its capabilities can be vastly different. You don't want to use a filter designed to trap 10- to 15-micron particles on an engine that needs control down to 2 or 4 microns.
That's why you need to make sure customers use a product recommended for the application. Maintain a good dialogue with your filter suppliers so you stay on top of any changes, says Marty Barris, director of product management for liquid filtration at Donaldson.
Make sure you cross-reference the part number in a cross-reference chart; many filter makers offer easy cross-reference look-ups online.
"When a customer goes to purchase an oil filter element from a source other than an OEM, they are taking a chance that it doesn't meet all of the OEM requirements, of which efficiency is only one of several," says David Cline, product manager, oil filtration systems for Racor Filtration. "Element performance, which includes micron ratings, is important when going outside of the OEM-supplied filter for cost reasons or when there is a need to have performance beyond the norm."
Some truck owners want to change the micron ratings of the filters they're using so they don't have to be changed as often. That may save them some filter changes, but it's going to cost them in shorter engine life in the long run.
"In many cases, buying a quality filter is a relatively small investment compared to the one they've made in that expensive engine or truck," Barris says.
Water in fuel
Filter makers and maintenance experts say with the advent of ultra-low-sulfur diesel, the industry has seen more problems with water in fuel.
Water, of course, promotes corrosion - and it increases wear on injectors and other fuel system components because it does not have good lubricity.
"We see it as an increasing challenge to effectively separate water" from diesel fuel, Barris says. "We know that with the advent of ULSD, because of the changes in refining and the need to add lubricity additives, which are essentially surfactants, it has become more difficult to separate water than the historical method."
Wix's Bandoly says water is attracted to some of the additives refiners are using to restore the lubricity that was removed along with the sulfur in the fuel.
Not everyone agrees that ULSD is an automatic water magnet. The issue has also come up in conjunction with reports of corrosion problems in fuel tanks, both on and off the vehicle, especially steel.
Whatever the causes, truck owners should do whatever they can to keep water out of the fuel. There are a number of filtration products that are marketed with fuel separation in mind.
Beware of biodiesel
Unlike the mystery over water in ULSD, it's well-known that biodiesel holds a lot more dissolved water.
Barris says straight biodiesel can hold several thousand parts per million of dissolved water before it reaches the saturation point - the point at which the water separates from the fuel and drops to the bottom of the fuel tank. In comparison, he says, petroleumbased diesel typically separates at only a couple hundredPPM.
Another problem with biodiesel, he says, is chemical incompatibility of elastomers and seals.
So if a customer is running biodiesel, suggest a product designed to be used with that fuel. Other features to look for might include higher capacity and better water-separation ability, along with seals made from compatible materials.
In addition, truck owners should be prepared to change fuel filters frequently in the period right after they start using biodiesel. It tends to act as a solvent and clean out some of the gunk that's collected on the walls of fuel lines and other fuel system components, clogging the filter. After a few changes, filter performance should go back to normal, says Dan Stibel, fuel filtration product manager at Racor.
Extended oil drains
Longer oil drains could mean a need for a more robust oil filter. Customers may want to go beyond the recommended filter specs if they're extending drains. Some filters are specifically marketed as being able to help extend drain intervals.
For instance, Cline explains, if a truck owner buys a filter that says it has a very high efficiency but doesn't consider its capacity, that filter may not have the contaminant- holding ability needed to perform properly throughout the extended drain interval.
"Once a filter becomes plugged or restricted to a pre-set point, then dirty oil is directed around the media, which sends dirty oil directly to the engine," he says. That's not good news for engine longevity, or satisfied customers.
"If you want to double your service interval, then you, in essence, need to double the amount of contaminants the filter can collect before it reaches the end of its life," says Jim Watson, director of engineering for liquid engine and filtration at Donaldson. A traditional cellulose-based filter may not do the job; you may need to move into filters with a synthetic media, says Watson's colleague, Rod Radosevich, engine marketing manager.
Jim Gambill, Delo brand manager at Chevron Lubricants, says in testing, "we have seen that in some cases, the same filters simply won't hold up for the extended service intervals."
As fleets extend oil drain intervals, they also may find those intervals become longer than the fuel filter is designed to last.
Bruce Stockton, former head of maintenance at Con-way Truckload and now a fleet maintenance consultant at Stockton Solutions, recommends fleets wanting to extend drain intervals use secondary fuel/ water separators to help bridge the gap between PM services and avoid pulling trucks in off the road just to replace fuel filters.
Another type of filtration offered for fleets that want to extend oil drains is bypass filtration, especially in severe or high-use areas such as refuse.
Kevin Kroger, president of bypass filter maker Puradyn, compares bypass filtration to kidney dialysis. A small amount of engine oil goes through an extra-fine filtration system on each pass through the engine.
On the other hand, Chevron's Gambill says addon filtration systems "can be overkill" and that highquality full-flow filters can do the job. One customer achieved 70,000-mile drains using Delo 400 LE 15W-40 and a high-quality filter. "Good filters were a key part of the story, but the add-on bypass filters were not necessary."
Contaminants and soot are only one piece of the puzzle when it comes to oil protecting your engine.
"Removing a smaller solid piece of particulate does not change the rate at which the oil oxidates or the [additive] depletion rate," Wix's Bandoly says. "Contaminant control is important for engine wear but not necessarily for oil life."
Engine oils are formulated with a complex balance of chemicals that perform functions such as neutralizing acids and preventing oxidation.
If a truck owner lets the oil go too long without changing, those additives break down. When this happens, not only is the oil not doing as good a job of protecting, cooling and cleaning your engine, but it also can lead to filter plugging. And if oil is overused to the point that the additive package drops out and forms sludge, Baldwin Filters says in a technical bulletin, it can plug not only filters but also engine passages.
That's why some filters aimed at extended drain intervals "re-additize" the oil, replenishing the protective chemicals. However, this practice is frowned on by some. "Engine oils must go through a costly and extensive testing protocol to meet API licensing approvals," says Mark Betner, heavy-duty lubricants manager at Citgo. Those API classifications set chemical limits
that are important for exhaust emission compatibility and overall performance. "How does adding additional additives along the way impact the formula and/or change the original formula?"
"We agree with the oil companies that you don't want to dump additives into the oil willy-nilly," says Puradyn's Kroger. He contends that some systems dump additives into the oil too quickly. "The release of additives into the oil has to be precise." His company, he says, has developed a way to release those additives more slowly.
At least one maker of a bypass system that additizes the oil says its product can only be used in pre-EPA 2007 engines. Newer engines require oil meeting API's CJ-4 standards; they feature lower ash and otherchanges needed to work with diesel particulate filters.
If customers are interested in a filtration system that introduces fresh additives into the oil, help them make sure it's designed to work with the oil specification they're using, and suggest they check with an engine manufacturer representative, especially if the engine is still under warranty.
One recent introduction to the market tackles the extended-drain and additive question differently. Wix says its EcoLast filter can double oil drain intervals because a chemical structure within its synthetic media sequesters the acid from the oil and traps it in the filter. It's not adding any chemicals but simply helping the oil's own additives last longer.
However, acid control is not the only factor limiting drain intervals. Oil also contains additives that address other areas of degradation, such as oxidation and nitration.
Oil filter trends
Another trend when it comes to oil filters is a return to cartridge-type filters.
Tom Pratt, a trainer at Penn Power Group, notes that cartridge filters were the norm for many years.
"Then for a while everything went to spin-on, and that was very convenient, but disposal became an issue," he explains. "Even using a filter crusher, you can only crush it down so far and you still have the metal case."
With cartridge filters, technicians can remove the media from a cartridge and dispose of it, then insert new media into the cartridge and re-install it on a truck.
However, Bandoly says, creating cartridge filters that can match the life and capabilities of a spin-on filter means entirely new designs. And eventually, new products for distributors to sell. These designs are already being seen in Europe and on Detroit and Mercedes-Benz engines sold in the U.S.
Filters are "a great upsell, especially on maintenance of the vehicles," Dobbs says. "There's always opportunities out there for helping the people, the public, to keep their engines going; that's what they look to us for.
"Truckers love it when things are explained to them. I think a lot of times, some of the issues or problems are that they're getting all their information at a truckstop instead of at a regular shop. A lot of engines have been built across the table from hamburgers."