| September 04, 2011 |
By Tom Jackson
To meet the many new exhaust emissions regulations, diesel engines have undergone more changes in the past eight years than in the previous 50.
The good news is the new engines still crank out plenty of torque-heavy power and do so with more fuel efficiency and cleaner exhaust than ever before. But one of the biggest challenges for fleet managers is understanding how the new engines, lube oils and fuel affect oil drain intervals.
Regardless of the year model of engine you are working with, there are five questions you have to ask before you can move forward on an extended drain interval program in today’s greener world.
What do you hope to achieve with an extended drain interval?
Defining your goals prevents you from doing something just to be doing something. Extending your lube oil drains just so you buy less oil can be a false savings. The oil drain interval is often a trigger for other maintenance events, inspections and safety reviews and those should be considered as well.
“Say you have a grease that can only go 250 hours,” says Dan Arcy, OEM technical manager for Shell Lubricants. “Even if you can go out to 350 hours with your oil drain interval, does it make sense to take that piece of equipment out of service at the 250-hour period if you’re not also going to change the oil? It may be a net loss to do that based on the productivity of the equipment.”
Arcy says he prefers the term “optimized” drain interval, rather than “extended.” Optimized implies that you are finding the best balance between the goals of protecting the health and longevity of the engine, saving money on maintenance and maximizing uptime. If you’re dealing with a lot of different types of equipment or equipment in different applications and environments, an optimized drain interval may mean one that’s timed at a service interval chosen for the worst case scenario – when the first fluid, oil component or grease that reaches its limits, Arcy says. Most fleet managers may not want to manage a lot of different drain intervals.
What are the limiting factors on my oil?
Most engine manufacturers publish specs on how much contamination or degradation they will allow in their lube oil. Once this limit is reached, you have to change your oil or face the consequences.
The challenge for today’s fleet managers is that those oil limiting or condemning factors have changed along with changes in engine design, emissions technology, ultra low sulfur diesel and new lube oil formulas. Here’s a summary of the major changes:
• Soot and heat increased in on- and off-highway engines from 2003 to 2010 with the increase in exhaust gas recirculation (EGR) to combat emissions.
• With the switch to selective catalytic reduction (SCR) technology in 2010, heat and soot became less of a problem for the oil.
• The use of diesel particulate filters (DPFs) both on- and off-road has significantly cut the levels of soot in the oil.
• The introduction of ultra-low sulfur diesel fuel for highway trucks in 2007 and for on- and off-road use in 2010 reduced the amount of acid formed in the oil and thus reduced the likelihood that TBN (or total base number) would be a condemning factor.
• Off-highway engines generally mirror the changes in on-highway, just three years later, with Tier 3 emissions standards being phased out and Tier 4 Interim and Tier 4 Final being phased in from 2008 to 2015.
• The new CJ-4 oils introduced in 2007 have reduced levels of sulfated ash, phosphorous and sulfur (called low SAPS oils). They protect the exhaust emissions componentry and offer better deposit control, improved wear protection and improved oxidation stability.
• The new synthetic or partial-synthetic oils, may help performance in some severe conditions. Their strong suit is engine protection especially against wear – offering high temperature oxidation stability. They also offer better cold flow properties which makes engines easier to start in severe cold conditions.
So oil chemistry has changed for the better and the contaminants and oil limiting factors have changed, some for the better some for the worse. Still, drain intervals are not as a general rule, getting longer. There may be six or eight potential condemning factors to watch for in your engines’ oil, but it only takes one of them to reach its limit to trigger an oil change.
“One of the myths I often run into is that synthetic oil allows you to extend your drain interval,” Arcy says. “But whether you have a mineral oil or a synthetic oil, if it’s condemned because of the soot level or dirt contamination it doesn’t matter. You don’t have the ability to go any further.”
What changes with my oil analysis?
Despite all these changes, one fundamental fact remains. To extend your drain intervals you need a good oil sampling and analysis program. And that begins, not with a spreadsheet and sample bottles, but a conversation with your oil analysis lab.
One of the first questions you need to ask is: do you have the right test package for an extended drain program? “A basic test package doesn’t include certain tests,” says Mark Minges, chief operating officer at Polaris Labs.
The three critical tests you need for extended drains include:
• Total base number (TBN). This measures the depletion of the detergent package that neutralizes the acids that build up in the oil.
• Oxidation/nitration. As the oxidation increases, the TBN depletes faster and the oil ages, eventually becoming unsuitable for use.
In addition to these elements for extended drains, any oil analysis should also include tests for wear metals, coolant, dirt, water, fuel dilution and soot.
“Our philosophy is that as long as the oil isn’t severely contaminated, as long as there is still base in the oil and oxidation and nitration levels are kept in check or below the warning limits then we’ll extend the drain out as far as possible,” Minges says. “If there is any contamination or an alarm level of contamination then all bets are off. What we don’t want to do is sacrifice the engine to extend the life of the oil.”
“I haven’t seen a fleet yet that we haven’t been able to extend to some degree.”
– Mark Minges, Polaris Labs
Even if you do decide to extend your intervals, Minges recommends to test your oil at the regular interval just to keep an eye on unforeseen problems that may prove catastrophic such as a breach in your air filters, or a sudden spike in wear metals. The use of an oil sampling port (see sidebar below) can make this sampling easier and less prone to contamination.
“Oil analysis is a window into your engine,” says Kevin Kroger, president and COO of puraDYN Filter Technologies. “It tells you what’s going on in your engine and the condition of your oil. It has to be a disciplined program, especially initially as you establish your hours. Oil analysis will help you get there safely.”
What should I do about my oil filters?
Assuming you want to save money and decrease downtime with an extended oil drain interval, one component you need to pay careful attention to is your lube oil filter.
“When you step outside the norm for drain intervals, you put more stress on the filter,” says Paul Bandoly, manager of technical services/customer training at Wix Filters. “The gasket that’s compressed between the engine and the filter base has to last longer. “The filter media has to be robust and durable enough to last for longer periods of time.”
Oil pulses through filters, and the unsupported cellulose media in traditional filters runs the risk of tearing as it gets hammered by these pulses in longer than normal duty cycles. To prevent this from happening in extended drain intervals filter manufacturers often use synthetic filter media and some kind of wire or mesh support, says Bandoly. “The fully synthetic sheets with the wire backing don’t flex the same, and since they don’t absorb moisture they don’t weaken, like cellulose,” over time, he says.
Bypass oil filtration is also frequently used to keep oil cleaner during extended drain intervals, says Neha Takawale, global product manager-lube filtration for Cummins Filtration. A bypass filter is a separate filter that siphons off a portion of the oil and cleans it, thus continually diluting the dirty oil with cleaner oil. Some bypass filters are included within the canister containing the full flow filters, some are housed in separate units.
With their high EGR rates and idle times, off-road machines often see a rapid buildup of soot in the oil, and bypass filtration is especially useful when dispersed soot content is the limiting factor on the drain intervals, Takawale says. And since soot particles are often sub-micron in size, they are difficult to trap in conventional cellulose or synthetic filter media of full flow filters.
Go or no-go?
Making the choice as to whether or not to extend your drain intervals should not be attempted until you’ve answered the above questions and discussed these issues with your equipment dealer, lube oil supplier, filter manufacturer and oil analysis lab. Only then can you identify your goals, plot a strategy and pencil it out to make sure it makes sense.
But the potential to save your company significant money and improve uptime is a likely benefit.
“With most of the samples we get from engines, I can look at the data and say there is no problem extending their oil drain out,” says Minges. “It depends on the unit, the duty cycle, the environment it operates in and the operator. But most companies change their oil too soon, and I haven’t seen a fleet yet that we haven’t been able to extend to some degree.”
Taking a clean oil sample from a warm or hot engine is tricky business. Pull a sample from drained oil and you pick up contamination from the drain plug, the oil pan, the collection container – anything that the oil touches. Vacuum pumps that suck oil out of the engine compartments are less prone to contamination but still require careful handling.
The best solution is to install an oil drain valve like the one shown here from Fumoto Engineering of America. Tapped into the oil lines upstream of the filter, the valve enables you to simply turn a lever to release oil and turn it back when your sample jar is full. Do it when the engine is warmed up and running and you get the most accurate sample possible. Even better, you can teach operators how to capture a sample in the field and avoid downtime or having to schedule a service tech to do it.
For more information see www.FumotoUSA.com.
Off road and truck fleet managers are under the gun to keep machines out of the shop and in the field as much as possible. To that end, filter manufacturers have come up with several innovative solutions that have the potential to cut the number of oil changes you may need in half.
Donaldson’s Endurance filters balance efficiency, capacity and restriction using the company’s Synteq filter media. While delivering low restriction and maximum flow, the synthetic filter media remove more than 90 percent of the contaminants that are 10 microns or larger compared to 50 percent for cellulose.
The Venturi Combo filter technology from Cummins Filtration consists of a section of full flow StrataPore synthetic media and a stacked disc layer consisting of high efficiency bonded cellulose media. The gradient density of the StrataPore media provides progressive removal of contaminant fine particles. The venturi nozzle in the filter works on the principle of pressure differential and directs more oil through the stacked disc media for high efficiency filtration without restricting oil flow.
Using what the company calls “Spin Flow” technology, the Wix XD Filter is a full flow bypass filter with channels in the top that direct the flow of the oil down the length of the element for a better mixture of the full flow stream exiting the filter. Instead of turbulence at the top of the filter, the XD filter efficiently uses the full length of the filter. Wix’s ecoLAST filter has a proprietary media that sequesters the acid in the oil that passes through it without changing the chemistry of the oil. That extends the TBN, which slows down the oxidation and degradation of the oil.
In addition to oil analysis you’ll want to keep an eye on oil consumption during an extended drain interval, says Kroger. Sometimes at the recommended drain interval, 250 or 500 hours, the oil may still be within the manufacturer’s specs for condemning factors but have just about depleted a percentage of its additive package.
When this happens the oil won’t lubricate as well and you’ll see increased oil consumption. As the oil begins to lose its lubricating properties it is more easily carried through different avenues into the combustion chamber where it is consumed. “You see a little more oil consumption because the oil is losing the characteristics that allow it to do its job, thus the importance of bypass filtration to keep the oil continuously clean and maintain its chemical balance,” Kroger says.
The change is small and the oil is still providing engine protection, but it would be wise to check the oil levels and top off when needed on any machine in an extended drain program.
The puraDYN Bypass Filter, used in conjunction with the equipment manufacturer’s full flow filter, keeps engine oil cleaner by cleaning a small amount of oil out of the normal stream and returning it back into the flow while also removing water and contaminating gasses. In addition the filter contains timed-release, additive pellets that replenish anti-oxidants, wear inhibitors and TBN and maintain viscosity as they become depleted from the oil. The filter also uses a treated element that chemically attracts and then binds contaminants less than one micron in size.