Grease has been called the "Rodney Dangerfield of lubricants." The late comedian was often known to lament, "I just don't get no respect." Likewise, grease is often an afterthought when it comes to truck maintenance.
Even Kirk Altrichter, vice president of maintenance at Gordon Trucking, a man who has a six-page slide presentation for technicians on the proper way to grease fifth wheels, admits "it's hard to listen to an engineer talk about grease for 45 minutes."
Nevertheless, Altrichter does pay close attention to his grease and greasing procedures. He uses three different types of grease: one for chassis items such as slack adjusters and ball joints; a synthetic grease for the differential and wheel ends; and another grease for fifth wheel top plates. His team has spent six or seven years experimenting with different greases to see what works best for the fifth wheel top plate, one of the toughest areas to keep properly lubed. And technicians for the Pacific, Wash.-based company, which operates about 1,600 power units, go through extensive maintenance training, including proper greasing procedures.
There are industry trends at work today that make it more important than ever to give your grease some respect.
One is extended oil drain intervals. Some fleets today are up to 30,000-mile engine oil change intervals, says Mark Betner, Citgo heavy-duty lubricants manager. If fleets do their "dry" maintenance at the halfway point, that means they're greasing at 15,000 miles. "That's not outside the range of a decent grease today," Betner says. "But some have eliminated that dry maintenance or moved it out beyond 15,000, and that's where you start to get into trouble."
Another trend that affects grease is the use of more corrosive de-icers on highways. If the grease gives out in your U-joints, for example, not only can you get water inside, but that water can be carrying magnesium chloride or calcium chloride. The resulting corrosion can literally wipe out the needle bearings, Betner says.
"I've found that guys who say they're not having [lubrication] problems are just accepting the problems as business as usual," Betner says. Fifth wheel repair or replacement, having to readjust the jaws of a fifth wheel every 100,000 miles, kingpin and U-joint replacement - these are all possible signs that your grease isn't working as well as it should, he says.
In order to think about grease, it helps to know a little bit about how it's made.
The main ingredient in grease is oil. Just as with engine oil, there are different types of base stocks, or it may be a synthetic oil.
Next there's the thickener, which in basically a type of soap, explains Dan Dotson, a lab manager for Valvoline in Lexington, Ky. Lithium and lithium complex are the most common, he says, but others, such as sodium, calcium, and barium, each have different performance aspects.
Finally, there are the additives, which handle tasks such as rust protection and resisting water washout. "Additives make a grease unique," Dotson says.
So there's a lot more that goes into grease than just slippery stuff.
"There is a lot of work [being done] around optimizing grease formulations to provide increased load protection, water spray-off performance, and longer performance life to reduce grease intervals and provide extended protection performance," says Leonard Badal, commercial sector manager for Chevron Lubricant Marketing. "In some of these formulations there is also focus on utilizing the benefits of premium base oils to provide additional performance capabilities of the greases." Chevron will be introducing several new greases to address extended maintenance intervals this year.
The right grease
The first thing to look at in choosing a grease is the owner's manual. The maker of the equipment will have specific requirements for lubrication.
One of the key requirements will be the NLGI classification for grease consistency. The National Lubricating Grease Institute has a system of automotive service grease classifications, established jointly with the Society of Automotive Engineers and the ASTM standards organization.
This NLGI system ranks greases from 000 ("triple-aught"), which is the consistency of cooking oil, all the way up to 6, which is very hard brick grease, the consistency of cheddar cheese.
For most trucking applications, you'll use NLGI No. 1 or No. 2. NLGI 1 is often used in cold-weather applications, especially where maintenance may not be done in a heated shop.
"A lot of people try to use No. 2 grease in some winter applications where they ought to be using No. 1 or aught (zero) grade grease because of the consistency of the grease," says Chuck Hamilton, technical service specialist for CHS, which makes Cenex brand lubricants. "If they want to get the grease pumped out of the cartridge at 20 below, they ought be using a No. 1 grease, because the pumpability is a lot better."
Indeed, pumpability of grease can be a "bugaboo," Betner says. "Your technicians will complain and you'll lose faith in the grease because it didn't pump well. There are products, especially synthetic greases, that will pump beautifully and you'll be happy with your grease."
Automatic lubrication systems might get down into the aught grades, such as 0 or 00.
NLGI also classifies greases with the terms LB for chassis and GC for wheel bearing. If you want a grease that can be used for both, look for a GC-LB designation.
There's more to a grease than how thick it is. Beyond the requirements of the equipment manufacturer, there may be other performance characteristics you want to consider for your particular application.
"A lot of times people judge heavy-duty grease by how tacky it is, and that's not always the concern," says Hamilton. They often look for grease that produces a long strand when stretched between the thumb and forefinger. But that doesn't necessarily mean it's a quality grease. In fact, notes the Technology and Maintenance Council of the American Trucking Associations, too much tackiness is a detriment to fuel economy. The grease offers too much resistance to movement.
"You want to look at the dropping point and what grease consistency you want in that operation and for the temperatures," Hamilton says. (Dropping point is the point at which the grease turns to a liquid, usually due to heat. You want a higher dropping point for higher-heat operations.)
If you operate in areas where corrosive de-icers are an issue, you'll want a grease that resists water wash-out. There's an ASTM test that measures how well a grease performs when exposed to synthetic sea water, Betner says. Other test results to ask your supplier about, he says, include temperature range, water washout, and 4-Ball Weld.
To help evaluate a grease, get your hands on the product information sheet, Dotson says, which will offer more information than you would get just from a label. Many grease manufacturers also have these sheets and other detailed information available on their websites.
Synthetic greases offer advantages in some applications, but they do have a higher up-front price.
"If you use a synthetic base, that improves long-term oxidation stability, but that's a cost," says Valvoline's Dotson.
Excellent performance at both high and low temperatures is the primary benefit to using synthetic grease, often translating into longer life for components. "You've really got to look at the componentry and see if there's a benefit," says Dan Arcy, Shell OEM technical manager. For instance, he says, if you have an automatic lubrication system on the truck, there are some benefits because of better flow at cold temperatures.
"You are seeing more and more of the full synthetics coming into play," says CHS's Hamilton. He notes that in addition to pumpability in co