Oils run the gamut from lower cost mineral-based oils to premium-priced semi-synthetics and full synthetics.
“Synthetic blends and fully synthetic oils cost more, but they offer value-added benefits that may offset the cost,” says Reginald Dias, director for commercial products, ConocoPhillips Lubricants.
There is a whole range of products currently available. “The demarcation line between synthetic and conventional oil is not distinct,” explains Ken Cicora, off-highway marketing advisor, ExxonMobil. “Totally conventional mineral oil is on one extreme and 100% synthetic oil is on the other side. In the middle, you have these synthetic blends that are a combination of cost/benefit. Semi-synthetics might have anywhere from 5% to 20% or more of synthetic (content). Therefore, you a have a range of capabilities.”
Choosing the product that provides the maximum return on investment really depends on your particular circumstances. In many off-highway applications, a premium synthetic oil is simply overkill. While premium oils do help extend oil drain intervals when used with a well-implemented oil analysis program, dirt contaminants are often the limiting factor. “The environment is sometimes your Achilles heel to being able to extend drains past a certain point,” says Cicora.
If you get a lot of outside contaminants in the oil, you reduce its useful life. “If contamination is present, then it is likely that you would not be able to enjoy the value-added benefits derived from synthetics,” says Dias.
“A lot of general construction outfits can do very well with conventional oils,” says Cicora. “You can extend drains with conventional oil if you have a good oil analysis program and the proper maintenance practices. You are not necessarily going to a point where the synthetic will give you that much more benefit. A conventional mineral oil is capable of getting you to that point.”
Synthetics Offer Additional Benefits
But there are circumstances where synthetics are the better choice. Synthetics have a higher viscosity index and therefore they are capable of handling a wide range of temperatures. “They have better pumpability on the low end and they also keep their viscosity better at the hot end compared to standard mineral oil,” says Cicora. “In addition, oxidation stability of synthetic oils is better than mineral-based oils, so they will last longer.”
This equates to added protection for your equipment. “A lot of the wear in machinery occurs during cold starts,” says Dias. “In the first few seconds that the engine is started, the oil has to be pumped to different parts of the engine. That is critical for the initial wear. Because synthetics have good cold temperature pumpability — also because they have good film strength at high temperature — you really get excellent lubrication for a wide range of temperatures.”
With the oxidation stability making longer oil life possible, and the benefits of the wide operating temperature range, why isn’t everyone switching to full synthetics? “The customer has to be very selective in choosing the synthetic lubricant that is applicable to the operation,” explains Dias. Not all applications will benefit from their value-added properties. “We will sit down with a customer, go over the operation and do a complete value/benefit analysis. We look at the cost of the product and the benefit. We also look into the life-cycle cost based on the drain intervals.”
An example of an application where synthetics have proven valuable is the bearing on top of an asphalt plant. “This bearing sees extremely high temperatures,” notes Cicora. “It is very difficult to keep the life of that bearing, so you use synthetic lubes.”
Perhaps one of the most extreme environments is faced by Alyeska Pipeline Services Co. The firm designed and built the 48-in.-diameter, 800-mile-long Trans Alaska Pipeline System. It maintains the pipeline from Prudhoe Bay on Alaska’s North Slope to Valdez.
This requires a diverse fleet of around 2,000 units — 1,800 are owned with approximately 200 rental units. The fleet is comprised of about 600 light vehicles, primarily diesel pickup trucks, and medium- and heavy-duty trucks of all types.
Construction equipment in the fleet runs the gamut from large excavators to Caterpillar D8 and D9 dozers. There are also front-end loaders of various types, 50- and 60-ton cranes and Caterpillar 14H motor graders.
This equipment must be ready to respond at a moment’s notice in the face of one of the most extreme operating environments in the world. “It can be as cold as -60º F or, on rare occasions, even lower than that,” says Dave Greenlee, fleet manager, engineering and projects division, Alyeska Pipeline Services. “On the high side, it might hit 90º F this weekend in the interior.
When you look at the Guiness Book of World Records, Fairbanks (the center of the pipeline) had the widest temperature extreme in the world. So you have to be prepared for a little bit of everything. We have to be able to respond in all types of weather year round.”
In some cases, routine maintenance on the pipeline is actually scheduled during winter because the marshes are frozen, making access easier.
In addition to the weather extremes, the equipment is operated in remote areas. “If you have a piece of equipment go down in a remote area, it takes a lot of resources to get that out and get it replaced or repaired,” says Greenlee. “You have to take that into consideration when you are looking at reliability.”
Synthetic oils supplied by ExxonMobil have provided a solution to these extremes. “We go through a lot of cold starts,” says Greenlee. “A cold start is where you get the wear on components, whether it is a hydraulic pump, an engine or a gearbox.” The oil doesn’t want to flow and protect critical areas from wear.
In addition, if the oil doesn’t want to flow, you will not be able to get the equipment started. “You have to bring in auxiliary heat. It is labor consuming and expensive,” says Greenlee. “Somebody has to man the heater. You burn fuel running the heater. It may take hours to get it warm enough to get it started.”
The high viscosity of synthetics ensures proper lubrication at startup and allows the equipment to start in extremely cold conditions.
Heat is also a consideration for Alyeska. High ambient temperatures and high load factors mean components do experience high operating temperatures.
“On a hill or different types of environments, you may be running right up against the redline as far as heat on that particular unit,” says Greenlee. “That’s where the synthetics really count. They give you extra protection on the high end. You need the protection to keep from having a total collapse.”
Trying to strike a balance of cold-start pumpability and high heat protection can be difficult with more conventional oils. Greenlee recalls problems with arctic hydraulic oils prior to switching to synthetics. “I specifically remember we were burning up hydraulic pumps on brand new cranes,” he says. “It was cold weather, but we were using a real lightweight arctic oil. It would flow in cold weather, but it didn’t have the protection for the pump components that was necessary.”
The use of synthetics has allowed Alyeska Pipeline Services Co. to reduce the number of lubricants in its operation. “We were kind of dabbling with synthetics in fleet applications in the 1980s,” says Greenlee. “In 1990, we made a conscious decision to consolidate the number of liquid lubricants that we were using. At that time, we were using about 12 different types of liquid lubricants.”
This inventory was necessary due to the wide temperature fluctuations. “In the winter, we would run these low-temperature lubricants,” says Greenlee.
“Then we would change to a summer weight in the spring. On the south end of the line where it was not as cold as the north end, they were using mineral-based lubricants. But there wasn’t a consistent, uniform policy.”
Weather fluctuations created problems with this approach. If it warmed up early, there was a scramble to figure out what to do. Conversely, if winter came early, the equipment was already filled with summer oil that needed to be quickly changed out. “Quite frankly, we were in what I would call a crisis mode,” says Greenlee.
Labor costs were a concern. “We would have to hire extra people to come in and change the oil in the spring and the fall,” says Greenlee. “Bringing all of these units in or changing oil in the field, out in the cold and snow, is difficult to do.”
In addition, there was a lot of wasted product. Oil had to be changed to accommodate the seasons regardless of the hours.
The higher priced synthetics end up saving money in the long run by addressing both labor and wasted product. The synthetics are able to accommodate the wide temperature fluctuations. “Instead of changing it in the winter and fall, we change it by utilization,” says Greenlee.
Instead of 12 different types of lubricants, Alyeska now only carries four. The three primary lubricants are all synthetics. “We use Mobil Delvac 1 engine oil that is formulated for diesel engines. We use a synthetic Mobil automatic transmission fluid (ATF) in all of our hydraulic applications. Then we use a synthetic gear oil, which is Mobil Trans SHC Arctic,” says Greenlee.
Using an oil that is capable of handling the temperature fluctuations has proven beneficial. “We haven’t had any problems. We don’t have anymore crises,” says Greenlee.
“There was a lot of skepticism when we went to the program, both internally from some of our own people and externally from some of the other suppliers who were not comfortable with it,” says Greenlee. But time has proven that this was a wise decision. “This whole time we have never had a failure due to lubrication. Part of my strategy is I want to use the best product out there to protect our investment in equipment and help us operate at the lowest cost in terms of maintenance expenses.”
Extending Oil Drains
While dirt contaminants may limit oil drain intervals, an oil analysis program and a high-quality oil can often lead to extended oil drain intervals. Alyeska Pipeline Services Co. studied this alternative closely. The air in Alaska often contains fine silt-like contamination from the constant wind gusts, so there was skepticism as to whether the extended drains would be possible.
“One of the big fears of extending the oil drain intervals was that the silt in the air and the contaminants blowing around all of the time were going to break down the oil,” says Dave Greenlee, fleet manager, engineering and projects division, Alyeska Pipeline Services. “We were going to break down the oil anyway because of contamination and other factors you run into with a fleet — fuel dilution, contamination from glycol systems, various things like that. The oil might last, but if we break it down through these other problems, then we are defeating the whole purpose.”
After exploring this option for many years, Alyeska made the decision to push oil drain intervals out to 500 hours. “We have not seen any problems and we have adjusted all of our PM schedules accordingly,” says Greenlee. “That is for large diesel engines for construction equipment.”
The hydraulic oils are sampled at appropriate hours. “If we haven’t had any contamination in that hydraulic system and the oil is still good, you can go almost indefinitely,” says Greenlee. The net result is a savings due to a reduction in the amount of fluids that you are using, a reduction in disposal costs and reduced labor requirements.