Grease 101 | Understanding The Do’s & Don’ts of Lubricating Grease
Lubricating grease. It keeps your equipment moving, whether your fleet consists of heavy machinery or heavy-duty trucks. Grease is a simple thing – and yet it’s not so simple. Just ask any fleet manager who’s responsible for maintaining a fleet of different types of lubricating grease and application tools.
Grease reduces friction between moving parts, from bearings to bushings, sliding surfaces to pivot points. The right grease, working properly, will smooth operation and prolong parts life by reducing wear and tear. The key is choosing the right grease for the job.
Lubricating grease is actually a specially-formulated compound
It is made up of three types of ingredients:
- Base oil (generally 80-90% by volume)
- Thickener (5-15%)
- Additives (2-5%)
Lubricating grease is much more viscous than machine fluids such as engine oil. Although both serve the same essential purpose, lubricating grease works differently. The thickener in the grease absorbs the base oil and additives, releasing them under shear force (two surfaces rubbing together under pressure to operate an equipment component). The grease “congeals” again when force is removed. Its high viscosity also allows grease to form an effective barrier to keep out contaminants.
Where things get tricky is that there are multiple types of base oils, thickeners, and additives that can be combined to produce lubricating grease. Specific ingredients depend on how and where the product will be used. It is this plethora of compounding options that make lubricating grease so versatile. But it can be difficult to choose the correct grease. And cost can vary significantly, depending on the ingredients.
Of course equipment manufacturers recommend lubricants – often by brand as well as performance specifications. But machines don’t always operate in average conditions. Performance properties of thickeners can affect water- and/or heat-resistance as well as the grease’s “consistency” – its ability to remain consistently in place under pressure. Base oils also vary, in viscosity and quality. They are chosen based on ability to withstand extreme temperatures or maintain consistent viscosity over a wide range of temperatures.
Additives boost anti-wear and anti-friction properties, and help guard against oil oxidation, rust and corrosion. They do that by:
- Enhancing the properties of the selected base oil
- Minimize any unwanted properties in the oil
- Providing additional properties not found in the base oil
Not all lubricating greases are compatible
If you’re a fleet manager with a mixed bag of machines, you have to stock different types of grease for different uses. It can be overwhelming to keep track of everything and ensure service techs are applying the proper product at the proper times in the right places. Therefore, it can be tempting to consolidate. Surely you could do with fewer options and use them interchangeably.
Don’t do it, advise experts. Although compatibility charts exist and they’re easy to find, they don’t tell the whole story. Often they don’t even agree on what is compatible with what. Typically, compatibility charts focus on thickeners, but even in instances where two thickeners will work together harmoniously, the base oil and/or additives could cause problems. It’s a complex science.
If you’re determined to pursue this, you can obtain the oil manufacturers’ product data sheets and then compare them to the grease specs for each piece of equipment in your fleet to see where intersections may lie. Or you could consult with a lab that specializes in lubricating materials.
An easier approach is simply to be systematic in storing and using lubricating grease. Color code your zerks and grease guns. Or use a different type of fitting for each grease type’s application gun, to avoid the possibility of misapplication.