Grease shows up twice on most construction projects. On the equipment side, it is the lubricant that keeps bearings, pins, and threaded fasteners working under load. On the facility side, it is the cooking byproduct that commercial kitchens must capture before it reaches the drainage system. The grease ant (Solenopsis molesta), also known as the thief ant, feeds on fats, proteins, and grease, and it is among the most common pest complaints in homes and food facilities across the United States, especially in kitchens. A grease ant colony in a building signals that grease is collecting where it should not be, which is why commercial kitchen designs include grease interceptor systems sized to capture fats, oils, and grease before they clog drains and sewer lines.
Construction machinery depends on the same principle in reverse: grease must stay where it is applied. The right grease reduces friction, excludes water and dirt, and protects metal surfaces, while the wrong grease, or the right grease applied poorly, leads to premature wear, seized fasteners, and failed bearings.
What Grease Is Made Of and How It Is Graded
Grease is a three-part system: a base oil that does the actual lubricating, a thickener that holds the oil in place, and additives that extend performance. The base oil, which makes up roughly 70 to 95 percent of the finished product, can be mineral, synthetic, or biodegradable. The thickener gives grease its semisolid structure, and additives handle oxidation resistance, rust protection, extreme pressure, and wear.
The most useful number on the label is the NLGI consistency grade, a scale that runs from 000, which pours like a thin oil, to 6, which is nearly solid. NLGI 2 is the default for most construction equipment because it stays in place on pins and bearings, resists water washout, and works with manual grease guns. NLGI 0 and 00 greases are used where grease must flow through long centralized lines, and NLGI 3 is chosen for higher-speed bearings and vertical applications. The dropping point is the temperature at which the thickener releases the oil and the grease stops being grease. Lithium greases typically soften in the 350 to 400 F (177 to 204 C) range, while calcium sulfonate complex greases can hold structure past 500 F (260 C). Those differences are why proper grease selection matters for construction equipment longevity on machines that work in heat, dust, and water all day.
NLGI grades at a glance
| NLGI grade | Consistency | Typical construction use |
|---|---|---|
| 000, 00 | Semi-fluid to fluid | Centralized lubrication systems, gearboxes |
| 0 | Very soft | Long supply lines, cold-weather operation |
| 1 | Soft | Central systems, low-temperature applications |
| 2 | Normal grease | Bearings, pins, bushings, chassis points |
| 3 | Firm | Higher-speed bearings, vertical surfaces |
| 4 to 6 | Very firm to block | Seals, blocks, specialty fittings |
Reading the rest of the label
Beyond grade and dropping point, look for three test results. The water washout test measures how much grease survives direct water spray. The four-ball wear test measures protection against scuffing under load. The Timken OK load test measures extreme pressure capacity. Strong water resistance and a heavy extreme pressure package suit excavator pins, crusher bearings, and other components that run outdoors.
Matching Grease to Threads, Bearings, and Pins
No single grease fits every surface on a machine. Threaded fasteners need a product that prevents galling and seizing. Rolling element bearings need clean grease with good shear stability. Pins and bushings in excavator buckets and loader linkages work under oscillation and shock loads that demand extreme pressure additives.
Greasing threaded fasteners and screws
Screws, bolts, and studs fail in a different way than bearings: they seize. Stainless steel fasteners are especially prone to galling, where metal transfers between threads and the fastener locks up mid-drive. Coating threads with grease or an anti-seize compound before assembly reduces friction at the thread interface, so less torque is required to reach the same clamp load. Lubricated threads typically need 20 to 40 percent less torque than dry threads, and the fastener comes apart again years later. On wood screws, a light coat of grease lets screws drive deeper with less effort and makes them easier to remove during renovation, a technique Fine Homebuilding covered in its piece on a better way to grease screws.
Bearings, pins, and bushings
Rolling element bearings want grease with good shear stability so the thickener does not break down as the balls or rollers churn through it. Pins and bushings want heavy extreme pressure protection because the load sits on a small contact patch that reverses direction constantly. That is where a single product shows its limits: a bearing grease optimized for speed may lack the extreme pressure additives a bucket pin needs, and a heavy pin grease may run too stiff in a high-speed bearing.
The right amount of grease
Volume matters as much as product. A bearing should be filled to roughly one-third to one-half of its free space, leaving room for the rolling elements to push grease aside and circulate it. Overgreasing forces the grease to churn, which raises temperature, consumes power, and can blow out seals. For pins, pump until fresh grease purges from the joint, then stop.
Why General-Purpose Grease Has Limits
An all-purpose grease simplifies inventory, and for light duty it works. Construction equipment spends its life in conditions that push any lubricant to its limits: heat from engines and brakes, dust that packs into joints, water from pressure washing and rain, and shock loads that squeeze grease out of contact zones. A product formulated to do everything acceptably usually does nothing exceptionally, and the gap shows up as wear.
Compatibility adds another layer. Greases with different thickeners are not always safe to mix. Lithium complex and calcium sulfonate products are generally not compatible, and mixing them can soften the grease until it runs out of the bearing or harden it until it blocks the fitting. In a fleet, that means dedicated guns, dedicated buckets, and labels on every container.
- Grease runs out of the joint within days of application
- Water turns the grease milky or washes it away entirely
- Pins and bushings show wear or scoring at the contact patch
- Bearings run hot to the touch after a few hours of work
- Fasteners seize despite regular greasing
Frequency, Quantity, and Monitoring
How often a machine gets greased matters as much as what goes in. Grease does not last forever: it oxidizes, picks up contamination, and gets pushed out of the load zone. Equipment manufacturers publish relubrication intervals, and daily greasing is routine for high-use pins, while bearings may run for weeks between services depending on speed, temperature, and contamination. Bearing manufacturers commonly report that more than half of premature bearing failures trace back to lubrication problems and contamination.
- Wipe the grease fitting clean so dirt is not pumped into the bearing.
- Clean the gun coupler and press it fully onto the fitting.
- Pump slowly in short strokes and watch for pressure buildup.
- Stop when fresh grease purges at the seal, unless the manufacturer specifies a different volume.
- Record the service in the maintenance log so intervals stay consistent.
Monitoring catches problems between services. High-frequency detection methods, including ultrasound, vibration analysis, and temperature checks, spot a bearing that is running dry or overpacked before it fails. Ultrasound is especially useful: a dry bearing produces a distinctive high-frequency signature, and the same detector confirms when fresh grease has quieted it.
Grease in Commercial Kitchens: Interceptors and Pest Pressure
The grease that attracts thief ants is a construction problem of its own. Commercial kitchens generate fats, oils, and grease with every service, and when that material goes down the drain it coats the inside of pipes, hardens, and eventually blocks the sewer. Plumbing codes in most jurisdictions require grease interceptors on commercial kitchen drains for exactly this reason. The interceptor slows the wastewater long enough for grease to float to the top and be skimmed off before the water reaches the sewer.
Sizing follows the flow. An interceptor is rated by flow rate in gallons per minute, and the design should hold wastewater long enough for separation, typically a few minutes of retention. A small cafe with a single sink might need a unit in the 10 to 20 gallon range, while a full-service restaurant with multiple fixtures can require 100 gallons or more. Undersized interceptors let grease pass through, and grease that reaches the sewer line produces the blockages and backups that facility managers end up paying to fix.
The pest connection closes the loop. Grease ants and other scavenging insects are drawn to the same fats the interceptor is designed to catch, which is why a clean, correctly sized interceptor is part of pest prevention in food facilities. Sealed lids, routine pumping, and prompt disposal of skimmed grease keep the building from becoming a food source for ants, cockroaches, and rodents.
Choosing a Grease That Lasts
For construction fleets, the practical decision usually comes down to lithium complex or calcium sulfonate complex. Lithium complex has been the workhorse of heavy equipment for decades: it is affordable, handles moderate temperatures well, and works in most pins and bearings. Calcium sulfonate complex costs more but brings two advantages outdoors: excellent water resistance and corrosion protection, plus a dropping point above 500 F. The multipurpose grease selection between the two depends on the environment the machine works in.
| Property | Lithium complex | Calcium sulfonate complex |
|---|---|---|
| Dropping point | 350 to 400 F (177 to 204 C) | Above 500 F (260 C) |
| Water resistance | Good | Excellent |
| Corrosion protection | Good | Excellent |
| Relative cost | Lower | Higher |
| Best fit | General fleet service | Wet, corrosive, high-heat duty |
A mixed fleet can justify both products: lithium complex for general service and calcium sulfonate for machines that work in mud, salt, or washdown environments. What matters is that each product goes only where it is specified and that nobody mixes them in the same gun.
The last piece of the system is the equipment that delivers the grease. A gun that leaks at the coupler, skips strokes, or delivers the wrong volume undermines even the best product. Grease gun best practices for contractors cover the basics: match the gun to the fitting type, keep the coupler clean, pump slowly, and verify that grease actually reaches the joint. Combined with the right product, the right interval, and a clean interceptor on the kitchen side, those habits keep grease working for the project instead of against it.