Grease has a finite working life. Once the base oil separates, oxidises or becomes contaminated, the grease can no longer form an effective lubricating film. At that point, friction increases, heat builds and bearing surfaces begin to wear. The re-lubrication interval – how often you replenish or replace the grease – is the single most controllable factor in preventing premature bearing failure.
The challenge is that no single interval works across every machine, load profile or environment. A conveyor idler in a climate-controlled warehouse and a crusher bearing on an open-cut mine site face fundamentally different conditions. This guide explains the variables that determine re-lubrication frequency and outlines how to build a schedule that reflects your actual operating conditions.
Understanding Grease Life
Grease life is the period during which a grease maintains its ability to reduce friction, separate moving surfaces and protect against corrosion. It is determined by the interaction of the base oil, the thickener system and the additive package with the conditions the grease faces in service. When any one of those components degrades beyond a critical threshold, the grease fails.
The OEM bearing manufacturer will typically publish a calculated grease life based on standard reference conditions: a specific speed, load, temperature and grease type. That figure is a starting point. In practice, the actual re-lubrication interval must be adjusted for the real-world conditions the equipment operates in.
Key Variables That Affect Re-Lubrication Frequency
Temperature
High operating temperatures accelerate oxidation of the base oil and can cause the thickener to release oil faster than intended. As a general rule, grease life halves for every 15 °C increase above the grease’s rated base temperature. In Australian conditions – where ambient temperatures regularly exceed 40 °C in inland and northern regions – this effect is significant. Conversely, very low temperatures increase grease viscosity, reducing pumpability and potentially starving the bearing of lubricant during start-up.
Load and Speed
Heavier loads compress the grease film and generate more heat at the contact zone, both of which accelerate degradation. Higher speeds increase the shear rate on the grease, which can cause mechanical breakdown of the thickener structure over time. Equipment running at or near its rated capacity, or subject to shock loading, will require shorter re-lubrication intervals than identical equipment running at partial load.
Moisture and Contamination
Water ingress is one of the most common causes of premature grease failure in Australian industry. Moisture washes grease from bearing surfaces, promotes corrosion and can react with certain additives to form abrasive by-products. Dust and particulate contamination have a similar effect, acting as abrasives that increase wear rates. Equipment exposed to washdown procedures, rain, high humidity or dusty environments needs more frequent re-lubrication and, in many cases, a grease formulated specifically for water resistance.
Equipment Design and Seal Condition
The bearing housing design, seal type and condition, and the presence or absence of purge fittings all influence how long grease remains effective. Open or poorly sealed housings allow contaminants in and grease out, shortening the effective interval. Where seals are worn, addressing the seal condition is as important as adjusting the re-lubrication frequency.
The Cost of Over-Greasing
A common response to uncertain re-lubrication intervals is to apply more grease, more often. This approach creates its own set of problems.
Seal damage. Excess grease increases internal pressure in the bearing housing, which can rupture seals. Once a seal fails, contaminants enter freely and grease leaks out – the opposite of the intended outcome.
Increased friction and heat. When a bearing cavity is overfilled, the rolling elements must churn through excess grease. This generates heat and drag, increasing energy consumption and accelerating oxidation of the grease itself.
Reduced bearing life. The combination of higher operating temperature and degraded grease from churning can shorten bearing life rather than extend it. In extreme cases, the heat generated by over-greasing is sufficient to cause bearing failure.
The goal is to apply the right volume at the right interval – enough to maintain a functional lubricating film without overfilling the housing. Where precision matters, a calibrated grease gun helps. Liberato stocks the 450 g Trigger Action Grease Gun, which delivers approximately 1.1 g per stroke for controlled application.
Selecting the Right Grease for the Application
Choosing the correct grease is as important as setting the right interval. The key selection criteria are NLGI grade (consistency), base oil viscosity, thickener type and additive package. These must be matched to the equipment’s operating speed, load, temperature range and environmental exposure.
| Product | Formulation | Typical Application |
| Black Tak | 5% molybdenum disulfide, lithium complex. Severe-duty mine and quarry grease. | Mining and quarrying equipment under extreme load and contamination. |
| Truck and Farm Grease | Ultra tacky, heavy-duty metal complex grease. | Trucks, agricultural equipment, general heavy-duty bearings. |
| Red Tacky Grease | NLGI 2, metal soap base with extra tacky additive package. | General-purpose high-performance applications requiring adhesion. |
| Super Blue Grease | Metal complex. Suitable for slow and high-speed wheel bearings. | Wheel bearings across automotive, transport and industrial. |
| Marine and Premium Wheel Bearing Grease | Calcium sulphonate base. Exceptional EP properties and water resistance. | Marine, coastal and wet environments. Premium wheel bearing applications. |
| Easy Flow Greases | Semi-fluid EP grease range. Designed for auto-lube systems. | Earthmoving, road transport and construction with centralised lubrication. |
Each product in the range has a product data sheet listing the NLGI grade, base oil viscosity, dropping point, EP properties and recommended applications. Request the data sheet before specifying a grease for a new application.
Building a Re-Lubrication Schedule
A practical re-lubrication programme follows three steps.
- Baseline.Start with the bearing or equipment manufacturer’s recommended interval and grease volume. Record the grease type, NLGIgrade and the operating conditions the recommendation assumes.
- Adjust for conditions.Shorten the interval where actual conditions exceed the baseline assumptions. Key adjustments include higher ambient or operating temperature, exposure to moisture or dust, loads above 50% of the bearing’s dynamic rating, and speeds above 50% of the bearing’s rated limit. Where multiple factors apply, the adjustments compound.
- Monitor and refine.Inspect bearings at each re-lubrication point. Note the condition of the purged grease:colour, consistency, presence of water or contaminants. Track bearing temperatures over time. If grease is consistently degraded at the scheduled interval, shorten it. If it remains in good condition, the interval may be appropriate or could be extended cautiously. Periodic grease analysis from a laboratory provides objective data on wear metals, oxidation and contamination levels.
Training and Application
Even the correct grease and a well-calibrated schedule will not deliver results if the application method is poor. Ensure maintenance teams understand the correct grease volume for each bearing point, the proper use of grease guns (including purge procedures where fitted), how to identify signs of over-lubrication and under-lubrication, and safe handling and storage of grease to prevent contamination before it reaches the bearing.
Clean grease guns, sealed storage and labelled lubrication points are simple measures that make a measurable difference to grease life and bearing reliability.
Next Steps
Liberato supplies a full range of industrial greases and dispensing equipment suited to mining, transport, manufacturing, agriculture and marine applications across Australia. If you need help selecting the right grease for a specific bearing, environment or duty cycle, contact us. We can provide the product data sheet, confirm compatibility with your existing grease and advise on the appropriate re-lubrication interval for your conditions. Call us or submit an enquiry through liberato.com.au.