The Spinner II bypass filter uses centrifugal force to fling particles to a wall that can be removed and cleaned.
T.F. Hudgins, Inc.
Gary Frisbe runs a 550-hp Caterpillar in over-the-road operations. “My Cat has 750,000 miles on it,” he says. “I do my oil changes at 12,000 miles and use the standard filter that came on the truck. I have not done an overhaul yet and don’t need one.”
Like Frisbe, many owner-operators stick to the filters that come standard with their trucks and change oil frequently. While that may be sufficient for some owner-operators, sometimes an inadequate or unmonitored filtration system can result in engine problems. To make the most of oil filtration – that is, to increase its benefit while containing costs – it helps to know what choices you have regarding a vehicle system that is largely hidden and seldom considered. It’s also good to practice routine oil analysis to make sure your filtration system is doing the job you expect it to do.
In addition to using a standard, full-flow filter, you have the option of adding a bypass (also known as part-flow) filter that siphons off part of the oil flow to remove smaller particles.
Some products combine a full-flow and bypass filter in one container. Stand-alone bypass filters are mounted between two hoses, one coming from an engine oil galley plug and a return hose going to the pan. Herman Miller, fleet equipment manager for Shopko Stores, warns that all bypass filters are not the same when it comes to installation. Some are gravity-flow; others are pressurized, and the type makes a difference in the placement of the hoses and the canister. Installation should be done only by a qualified mechanic. If your engine is still under warranty, consult with your dealer before investing in a bypass filter.
Full-flow filters trap the larger particles. If your full-flow filter gets clogged, a valve opens to relieve the pressure and lets unfiltered oil and debris flow through the engine. That limitation creates a need for bypass filters, but bypass filters also have other functions.
“Full-flow filters scavenge particles between 20 and 30 microns, while part-flow filters remove 85 to 90 percent of particles between 5 and 20 microns,” says John Clevenger, product manager at Fleetguard. Bypass
filters pull in only about 10 percent of the oil – between 2 and 3 gallons per minute – at a time and pass it through to the sump. They are capable of holding onto particles as small as 2 microns, which is the smallest size that can be accurately measured. Most bypass systems clean all an engine’s oil about five times per hour.
Acids, metals, water, soot and other solids contaminate oil and cause engine wear. As contamination levels rise, the additives in oil – not the base oil – become depleted and break down. This contamination restricts the ability of additives to reduce deposits and to hold solids in suspension. Sludge, which accounts for about 80 percent of oil contamination, is the most significant cause of engine wear, Clevenger says. But you can’t rely on your dipstick to tell you what’s going on in the crankcase. Within half an hour of running new oil, it will turn dark. The only real protection you have for your engine is filtration.
If you run heavy loads (producing more soot, acids and metal wear), north to south (causing water to condense due to drastic temperature changes), or in harsh or dusty conditions, consider using the more expensive synthetic media filters. They are designed to catch smaller particles.
Filters not only remove solid contaminants, but also reduce the amount of water and fuel mixing with oil. Luber-finer and Puradyn have different solutions for this problem. One of the major components of Puradyn’s part-flow filters is an evaporation chamber that aids in the evaporation of fuel and water, says Priss Neulander, media coordinator.
Most part-flow filters do not have evaporation chambers. This is partly because all filters remove some water and fuel without the addition of such a chamber, says Jack McCoy, heavy-duty marketing manager for Luber-finer. Also, if oil is running at the optimum temperature of 180 to 220 degrees, even more water and fuel will evaporate without additional technology.
However, Frank Lotz, product engineering manager at Puradyn, counters that some of the evaporation is an illusion. “Water and fuel evaporate when the engine warms up and condenses on the walls of the engine,” he says. “When the truck cools down, these pollutants recondense into the oil. The water helps form sulfuric acid, and the fuel causes loss of viscosity. In Puradyn’s system, these pollutants are vented directly from the evaporation chamber into the atmosphere.”
McCoy agrees that starting a cold engine in cold climates tends to allow the accumulation of fuel and water in oil. To counter this, Luber-finer has come up with a thermostatically controlled filter that kicks in at 110 degrees.
Some original equipment makers spec bypass filters as standard equipment. Mack uses a system of its own, while Cummins uses Fleetguard’s Venturi system. The Venturi is a multi-media filter, meaning it has a bypass filter and a full-flow filter in tandem. The standard filter for Caterpillar is full-flow without any part-flow capability, says spokesman Chuck Timmes. At Detroit Diesel, Chuck Blake, systems engineer, says Detroit has gone to a tightened full-flow material that now catches particles as small as 25 microns instead of 40 microns. Detroit uses two full flows in tandem or two high capacity synthetic filters.
McCoy at Luber-finer says his company does not promote the use of bypass filters to extend oil change intervals except when they are used in conjunction with requirements of OEMs, fleets and oil companies.
One version of a bypass filter is the centrifuge filter. T.F. Hudgins Inc.’s Spinner II, similar to Vortex and other centrifuge filters, uses the engine’s oil pressure to spin an internal turbine 6,000 to 8,000 rpm, thereby creating a gravitational force 2,000 times the pull of gravity. This flings particles against the filter’s wall and collects them in the rotor bowl. A clay is formed that can then be removed at regular service intervals.
Centrifuge filters, or spinners, handle soot and wear debris only, says Jim Weaver, executive vice president of T.F. Hudgins. They are meant to be used in conjunction with full-flow filters, but not with other bypass filters. Spinner II centrifuges are reusable and cannot clog, according to Weaver. Like other bypass filters, centrifuges use about 10 percent of excess flow and clean all the oil about five times per hour.
Miller at Shopko, who believes bypass filtration extends oil-drain intervals, bases his oil management program on bypass filtration. But his faith comes with a number of qualifications. “You need to do consistent oil analysis, and you need to find a good lab,” he says. Joe Storey, an owner-operator who hauls extremely heavy loads for Miller Transfer and Rigging, agrees. “Oil analysis can find emerging problems before they get out of hand,” he says.
Consistency is important because oil analysis done on an irregular schedule will not allow you to spot a particular contaminant as it builds up in your oil. Wear metals are one example, says Mike Reimann, president of Petroleum Technologies in Grand Rapids, Mich. “Upward trends in iron, chromium, aluminum might point to excessive piston wear; lead, copper and tin could mean there is excessive bearing wear. Potassium, sodium or molybdenum in high amounts indicates coolant in the oil and a mixture of chromium, aluminum and fuel could point to an injector problem or merely an abundance of cold weather starts,” Reimann says.
Despite the variety of filtration products, some contaminants will remain in oil. To give your engine the longest possible life, use routine oil analysis to keep an eye on your filtration and other systems, and consider improving your filtration system or adjusting your drain cycles if necessary. Trying to save money by adjusting drain cycles can be counter-productive and will almost certainly be with an exhaust gas recirculation engine. Unless you are diligent about analysis and getting extremely accurate oil samples, extending drain cycles should only be done in consultation with your OEM and other experts.
NEW ENGINES, NEW FILTRATION DEMANDS
The cooled exhaust gas recirculation engines developed to meet the tough emissions standards that became effective Oct. 1 make decisions about oil and filters more critical. EGR systems dump more soot and acids into oil as exhaust is recirculated through the engine.
Increased soot, however, has been a bigger problem since 1998, when engine makers retarded timing on diesels in response to regulations requiring a 20 percent reduction in nitrous oxide emissions. Consequently, if your engine was made in 1998 or later, you may want to consider bypass filtration not so much to extend oil-change intervals but to handle increased soot levels.
John Clevenger, product manager at Fleetguard, says no one knows how much acid is produced by EGR engines. “It will take 12 to 18 months of testing EGR in the real world to find out,” he says.
CI-4 oil is the latest oil standard, developed to handle the added soot and acid without extending pre-October oil-drain intervals. Owner-operators, many of whom will buy EGR engines in their next trade cycle, will want to consider at that point if sufficient data has been gathered regarding the effectiveness of CI-4 oils and how filtration systems handle them. While CI-4 oils do keep soot in suspension better than previous oils, they remove soot only when it has agglomerated. Before this level of agglomeration is reached, soot continues to circulate. Extensive testing was done by all the engine makers before October, but little if any testing was done on the effect of extended drains, says Clevenger. These factors make conservative drain intervals for EGR engines a very good idea.