Choosing the Right Lubricant for Your Construction Equipment

The current and future state of engine oil

When we talk about lubricants, most of us immediately think of engine oil, so let’s start our discussion there. Increasingly stringent emissions standards drove oil development for several years. The last iteration was CK-4 oil, which remains the current category.

Before an oil category is finalized, it’s referred to as a “proposed category” and gets the initials “PC.” PC-11 led to CK-4. The current proposed category is PC-12. This anticipates new emissions standards proposed to implement in 2027. Two primary things will happen: Oxides of nitrogen (NOx) will be drastically reduced, and the required service life of exhaust after-treatment systems will be significantly extended.

Much of this is driven by the on-highway market but eventually affects all applications for most diesel engines. “There’s continued interest, especially in on-highway, for increased fuel efficiency,” says Shawn Whitacre, Senior Staff Engineer, Chevron. “Oxidative stability is a key driver in PC-12 as fuel efficiency measures can drive up operating temperatures because of such things as changes to fuel injection mapping and waste heat recovery. There’s also a move toward higher oil temperature thermostats to keep oil thinner. Oil rifle temperatures are moving from 105 degrees to as high as 120 degrees.” In off-highway, Whitacre says the move is to extended change intervals, from 250 to 500 and even as high as 1,000 hours.

When PC-12 is finalized as the new category, it will likely include new viscosities. While those oil weights will probably not include the 0W-16 now available for direct-injection gasoline engines, Whitacre says 5W-20 is likely and maybe a 0W-20; 10W-30 is the standard now. He says FA-4 oil is for specialized applications and is not prevalent in the off-highway market and is not suitable for use in most older engines.

Lubrication is more than engine oil

Roger Collard is the Engineering, Maintenance, and Reliability Manager for the Royal Purple and Bel-Ray brands of Calumet Specialty Products Partners, L.P. Both brands have extensive catalogs of products for the construction equipment market.

Collard says synthetics are making their way beyond engine oils into such products as gear lube. “Synthetics are often the right choice, but not always,” says Collard. “Sometimes it’s a synthetic, sometimes a synthetic blend, sometimes a mineral-based oil. The objective always is film strength and to maintain a 2- to 3-micron lubricant film thickness between moving parts. Discuss your needs with your supplier to find the right product.”

Collard says modern greases most often use lithium complex soap as a thickener, although aluminum complex soaps, polyurea, and calcium sulfonate are also found, as is bentonite clay, the standard thickener for decades. The biggest concern for grease is handling temperature extremes, not only maintaining protection in high heat but also retaining pumpability in cold conditions. “Key considerations in grease selection are a quality oil of the proper viscosity for a given RPM, the thickener type, and the viscosity index.” Standard base oils have a VI of 90 to 100; synthetics often have a VI of 150 or higher. “A higher viscosity index indicates less reactance to heat and cold.”

With hydraulic fluids, “some systems require zinc-free fluids, others require ashless.  Check the specs. The big issues are foaming, oxidative stability, and demulsibility, which is the ability of the fluid to separate from water and not emulsify.”

Viscosity is the number one spec with gear oil. “Are you using OEM spec? If not, why not? It may be prudent to deviate from OEM spec but only if there’s a solid underlying reason based on application, not preference or tradition.”

Final tips on having the right lubrication program

Both experts advise against the use of engine oil additives, noting that oil is a carefully engineered, fully formulated product. There are limits on sulfur, phosphorous and sulfated ash, says Whitacre, but not other chemicals. Additives can bring levels of any chemical above optimal limits. “In addition, some additives include incombustible products that clog the DPF over time. DPF is more sensitive to ash, while SCR is more sensitive to sulfur and phosphorous.” Neither after-treatment system responds well to oil additives that inevitably find their way into the exhaust stream.

Collard says, “’What about additives?’ We get this question all the time” Because additives upset the careful chemical balance of any modern oil, they should not be used. The potential for disruption of the chemistry is high. “The wild card is typically the esters, and there are many variations of them.”

Both also advocate for the use of oil analysis. “It’s fast, affordable, and can provide results in 24 to 48 hours by email, text, or within an app,” says Whitacre. “It can help you optimize your service intervals and provide insights for pre-emptive repair, thereby preventing downtime.”

Collard says Fourier-transform infrared spectroscopy (FTIR) is especially adept at identifying chemical changes and degradation in used oil. “It’s often an added expense so customers may want to do it only periodically, not with every oil sample.” He says analyses that find no undue contamination or wear have value. “Even if your whole fleet comes back green, there’s value in those results. You are not just looking for problems; you’re also confirming the suitability of your oil choice, asset condition, and the effectiveness of your maintenance program. Knowing the condition of your equipment facilitates planning and cost avoidance.”

Whitacre offers two final tips. “Fluid cleanliness in general is essential. Producers and dealers go to great lengths to ensure cleanliness and customers should follow through.” Cleanliness includes properly vented storage tanks plus the cleanliness of transfer equipment, shop cloth, funnels…anything touched by any fluid.

Also, mind your idle time. This can be challenging with so many modern machines offering auto-idle. “At idle the combustion process is less efficient, resulting in the production of more contaminants,” says Whitacre. “Also, the engine oil temperature is lower making it harder for such contaminants as water and fuel to evaporate.”

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