By John Smith
Mark Betner admits that grease choices are often an afterthought in many maintenance shops. Specifically, Citgo’s product manager, heavy-duty lubricants, puts it another way: “They’re unloved, un-thought about, un-talked about.”
Unloved they may be, but the choices behind different chassis lubricants are becoming more important with every passing year.
“When I started out in this industry, there were people doing their ‘A’ maintenance at 3,000 miles,” Betner recalls.
When oil drains were extended, however, shop personnel also needed to wait a little longer for opportunities to apply a fresh layer of grease to king pins, slack adjusters, cam bushings, unsealed U-joints, springs and shackles.
Then the challenges can emerge.
Perhaps it starts with a small amount of water coming out of a U-joint; maybe it leads to other corrosion-based issues. The growing popularity of de-icing solutions such as magnesium chloride has certainly compounded the problems that can occur.
“If the grease is displaced and water intrusion is the next step, then that water is not coming in as distilled water. It’s coming in with magnesium chloride,” Betner says. “So your corrosion rates of your needle bearings and your U-joints or any articulated pins are multiplied many times over. You have to have a very good anti-corrosion product in place to handle that.”
Some of the potential challenges have been solved through the introduction of sealed components or automatic lubrication systems. Still, fleets continue to operate a lot of equipment that relies on a technician’s skilled application of the grease gun.
GREASE FORMULAS AND FEATURES
The first step in any application should be to ensure that the grease in the application gun is specifically designed for heavy-duty service. “Most all-purpose greases are made with a base oil that would be the equivalent of about an SAE 30-grade oil,” Betner explains.
Greases also can be optimized for specific uses. When Shell was developing a new formula for fifth wheels, for example, it ensured that 25 percent of the mixture consisted of a lithium-based thickener and solids such as graphite.
“That thickening agent is more resistant to water,” says Dan Arcy, OEM technical manager with Shell Global Solutions. “There’s less spray-off.”
But a grease’s formula also can involve trade-offs between one feature and the next. Says Betner, “The more muscle you put in a grease for staying power, the more difficulty the pumpability or the dispensability. You have to ask yourself, ‘What temperature conditions can I pump this grease under?’”
The solution to this challenge can involve the use of synthetic formulas. The combination of synthetic base oil and a functional synthetic polymer, for example, allowed Citgo to improve the pumpability of one formula by a factor of 3.5, when compared to one of its mineral-based greases. Conventional and synthetic greases also can be mixed in a component, although that can sacrifice some of the enhanced performance properties that are supposed to emerge with the advanced lubricants.
The real issue with compatibility between one grease formula and the next might involve the different thickening agents that promise benefits such as better corrosion protection or resistance to water.
“It’s not automatic that two thickeners would fight each other, but if it’s not a lithium base, ask your supplier about the compatibility with aluminum and polyurea and calcium-type greases that are out there,” Betner stresses.
It is the type of information that could prevent callbacks. A shop may apply a superior grease to a leaking U-joint, but incompatible formulas will simply leak right back out – and that could lead to complaints about the quality of the new grease that was used.
“The two of them can be incompatible and they can soften, so it doesn’t hang in as well,” agrees Arcy.
In contrast, lithium complex greases are compatible with lithium and other types of thickeners. It is simply a matter of being aware of the products that are used.
COMPONENT SPECIFIC USES
But it is not the only compatibility issue that can emerge with a lubricant on the chassis.
For example, a synthetic transmission fluid may offer many benefits over a traditional 75W90 or 80W140 formula, but its Extreme Pressure (EP) additives have been known to attack soft metal elements such as synchronizer bushings, Betner says. “It’s not universally automatic that you have to separate the two, but that’s been a big accepted practice.”
The differences in formulas can be particularly important when working with a rebuilding shop.
“It’s really hard to purge a motor bearing,” observes Jerry Rainsdon, marketing director for commercial lubricants at ConocoPhillips.
Auxiliary power units (APUs) deserve synthetic lubricants of their own, Arcy adds. A synthetic 5W40 oil, for example, will ensure easier starts in cold weather – and that can be particularly important given the way this equipment is used. The added protection is even welcome during warmer weather. “There’s limited air flow around APUs. These things are getting hot,” Arcy explains.
Shawn Ewing, ConocoPhillips’ technical service coordinator, commercial lubricants, suggests that synthetic base stocks have made their biggest impact of all on drivetrain components such as transmissions and drive axles. They have certainly made it possible to offer “fill for life” properties in components such as U-joints and suspensions.
“If you’re using a 75W90 full synthetic driveline lubricant, you’re getting fuel economy back on that,” Betner adds, referring to how some driveline manufacturers are claiming improvements of as much as 5 percent. In the process, that lubricant is also offering better protection for rings and pinions down to temperatures around -40˚ F.
Contrast that with an 85W-140 which is only good to about 10˚ F or even an 80W90 which is only good down to -10˚ F. Differentials protected by a synthetic lubricant also will tend to run about 40˚ F cooler than those that are protected by mineral-based formulas.
When it comes to the application of any grease, however, it is also important to remember that there can be too much of a good thing. “Most grease failures are from over-greasing,” Ewing says, noting how that will blow out seals and welcome contaminants in the process.
Paula Del Castilho, Petro Canada’s category manager, commercial transportation lubricants, suggests that shops in the aftermarket should see the array of options as a business opportunity.
“Talk to customers about everything,” she says, walking through a display at the Technology & Maintenance Council’s recent trade show. “Sometimes they’re looking for a single supplier.”
