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Grease vs. Oil: Differences & Choosing the Right Lubricant
Grease and oil represent two common types of lubricants. Both reduce friction, protect against contaminants, and regulate operating temperatures. Selecting the proper lubricant is vital to the health and function of whatever machine you’re servicing.
The guide below explores the differences between grease and oil to help you understand which best suits your intended application. Discover where and how grease and oil excel to improve machine longevity and performance, reducing costly downtime and expensive repairs.
Partner with Cadence to source high-quality grease and oil for your automotive or industrial needs.
What Is Grease?
Grease is a type of semi-solid lubricant used for a variety of applications where the lubricant must remain in place rather than flow through passageways. Numerous applications call for a variety of grease types, not necessarily based on color.
Greases are comprised of a base oil, thickening agents, and additives:
- Base oils: It’s vital to match the viscosity of base oils — typically mineral oil — to the machine’s operating conditions. Low-viscosity oil performs well in colder temperatures, while high-viscosity oil is ideal for hotter conditions.
- Thickeners: Organic and inorganic soaps — such as metallic soap — are common thickeners. Other examples include lithium, aluminum, and calcium.
- Additives: Similar to the additives found in oil, grease additives help reduce friction and wear. The type of additives that best suit the application vary based on compatibility, performance requirements, and cost.
The National Lubrication and Grease Institute (NLGI) classifies grease from soft (000) to hard (6) based on its consistency. Softer greases offer better lower-temperature pumpability and service, while harder greases are ideal for sealing leaks. Greases classified as #2 are some of the most common in the automotive world.
What Are the Main Types of Grease?
Although all greases tend to retain a similarly thick consistency, there are significant differences between the various types.
Lithium grease is common for general use, but silicone grease is fairly popular in the automotive community. The type of grease suited to your application depends on its various features.
Lithium Grease
Lithium-based grease is often used in wheel bearings and U-joints as it resists the damaging effects of water and higher operating temperatures. Stable and effective, it’s ideal for general-purpose use.
Silicone Grease
Silicone grease is non-reactive to plastic and rubber. It can withstand extreme operating conditions, including immense pressure and brutal temperatures, well beyond the scope of the automotive world.
Calcium Grease
A cost-effective, water-resistant lubricant, calcium grease favors applications in a stable operating environment that doesn’t see higher temperatures or extreme pressures. Calcium grease is not to be confused with calcium sulfonate grease, which is typically used for marine applications.
Molybdenum Disulfide Grease
Often referred to as “moly” grease, molybdenum disulfide grease relies on its disulfide additive to reduce wear and increase protection in extreme-pressure circumstances. Moly grease is a general-purpose grease that’s known for its slick, lubricating properties.
Polyurea Grease
Ideal for heavy loads and a long service life, polyurea grease is commonly used in electric motors. This type of grease has excellent stability at higher temperatures and resists water well. Polyurea grease consists of a synthetic base oil and polyurea thickening agents.
What Are the Pros of Grease?
Although many other greases are available besides those discussed thus far, each offers similar benefits and drawbacks. Explore the advantages of grease below:
- Absorbs noise and vibrations
- Seals to prevent further leaks and contamination
- Protects against corrosion, even during downtime
- Absorbs water without changing its properties
- Minimal amount required to cover a large surface area
- Pump or filter not required
What Are the Cons of Grease?
That said, grease can also have some downsides. Keep these in mind:
- More easily generates heat
- Consumes more energy
- Over-greasing can lead to increased friction and heat
- Fails to dissipate heat as effectively
- Not ideal for high-speed machinery
What Is Oil?
Industrial and motor oils are two common forms of viscous lubricants that help everything from passenger vehicles to complex machines function properly.
Derived from animals, vegetables, or — as is most common in the automotive industry — petrochemicals, oil comes in several forms, including conventional and synthetic. As the saying goes, oil and water don’t mix.
What Are the Pros of Oil?
The next time you reach for a lubricant, consider whether oil can complete the job. Here are some advantages of oil:
- Excellent temperature control
- Easy to drain and replace
- Lower viscosity allows it to flow in colder temperatures
- Ideal for high-speed applications
- Consumes less energy due to viscosity
What Are the Cons of Oil?
Although oil goes where grease necessarily can’t, it’s not always the better solution. Here’s how oil might fall short:
- Higher frequency of maintenance intervals
- Requires a closed system
- Improper oil weight or type can damage critical components
- Prone to buildup
- Viscosity varies depending on temperature
When To Use Grease vs. Oil
Follow the manufacturer’s guidelines when selecting between grease and oil. Grease tends to have a higher viscosity, which enables it to stay in place during use. However, oil’s low viscosity allows it to penetrate smaller spaces and dissipate heat faster.
Grease
Grease excels in extremely hot or pressurized operating environments that demand more lubricant. Because it stays in place, grease can also seal components against contaminants with a nearly solid barrier. Turn to grease for isolated systems, open bearings, heavy loads, and high-output machines.
Oil
High-speed, low-drag applications demand oil’s flow to promote efficiency, dissipate heat, and remove contaminants. Oil can get into places grease can’t, which is why it’s effective in vehicle engines, among other machines. However, oil must be used in a closed system to prevent any leaks.
High-Quality Lubricants From a Company You Trust
It pays to know the difference between grease and oil, especially regarding proper industrial machinery maintenance and care. Don’t settle for inferior lubricants that can create more problems than they solve. Call the experts at Cadence today at 336-629-2061 to discuss your lubrication needs.
Sources:
Polyurea Greases | Society of Tribologists and Lubrication Engineers