How to Select the Right Fluid for Your Hydraulic System

The right hydraulic fluid makes all the difference to the performance and longevity of your hydraulic system. Learn more about the characteristics that matter most and how to find a hydraulic fluid with the right performance and protective properties.

How Hydraulic Fluids Affect Pump Performance

Hydraulic systems comprise both physical components and hydraulic fluid. Just as the right components are necessary for a smoothly running pump, the proper fluid is also critical. To achieve optimal performance, the hydraulic fluid must possess the right viscosity, quality and fluid type. Additionally, it’s crucial to ensure that the fluid is free of any contaminants.

But if your system doesn’t have fluid with the right qualities, it can result in:

• Damage and short-lived components
• Less efficiency and more heat due to a lack of lubrication
• Buildup like sludge and varnish
• Corrosion

Fluid Property Considerations

As you source a hydraulic fluid for your system, it’s important to look for the following key characteristics, with viscosity being at the top of the list.

Viscosity

Fluid viscosity dictates every aspect of how a fluid interacts with the components of a hydraulic pump. Consider its effect on:

• Filterability
• Air release
• Cavitation
• Heat dissipation
• Both elastohydrodynamic lubrication and boundary lubrication
• Volumetric efficiency, or how efficient the fluid is if there’s a leak
• Mechanical efficiency, or how efficient the fluid is if there’s mechanical loss caused by internal friction

When the viscosity is low, the fluid is thin, drastically increasing the risk of heat buildup and damage due to metal-on-metal contact. There is also an increased risk of a leak, which can result in fluid loss over time. But if it’s too thick, or viscous, it will be too sluggish and take much more effort to move. Thick fluid can also lead to poor air release and cavitation, interrupting the flow. These incidents will lead to insufficient lubrication.

It’s not enough to consider a fluid’s room temperature viscosity. Along with ambient temperature characteristics, the fluid will have different characteristics at different operating temperatures. Even the pump’s design could affect the viscosity.

Other Crucial Considerations

Once you have calculated the right viscosity for a given fluid, you must also consider other characteristics that impact the fluid’s performance. These include:

• Anti-wear properties: Anti-wear additives can alleviate the risk of direct metal-to-metal contact with thin fluids. Zinc-based additives, or zinc dialkyl dithiophosphate (ZDDP), are the most popular type of anti-wear additive. Zinc-free additives, however, are a superior choice for reducing the risk of hydrolysis, corrosion or environmental harm.
• Viscosity Index (VI): High-VI fluids stay viscous at high temperatures, while low-VI fluids do not.
• Thermal and oxidation stability: You may need a fluid that resists oxidation due to water, heat or the presence of wear metals. Oxidizing oil creates acidic byproducts.
• Air release: Having air trapped in the system can lead to cavitation and reduced efficiency.
• Foaming: Fluids can develop the tendency to foam if they’re contaminated by degraded byproducts, water, air or other factors. System design can also increase agitation and, as a result, increase foaming.
• Filterability: An oil that can be passed through a filter to remove contaminants without removing important additives is desirable as the filtration will increase its effective lifespan.
• Demulsibility: This characteristic measures an oil’s ability to release water, which is especially crucial in humid environments.
• Rust and corrosion inhibition: Some fluids have rust inhibitors that thinly coat metal surfaces and reduce the risk of corrosion.
• Material compatibility: Carefully select a hydraulic fluid that won’t degrade any rubber or elastomeric gaskets, seals, hoses or accumulators.

How to Select the Right Fluid

Now that you know what qualities to look for in a hydraulic fluid, follow these steps to select the right fit:

1. Find a hydraulic fluid rated to perform at the system’s standard operating temperatures.
2. Narrow down the possibilities to fluids with anti-wear additives.
3. Note the VI index rating of each fluid. It’s best to have a thick fluid — and one that will stay thick — if the machinery operates at high temperatures or in extreme conditions.
4. Find a fluid with a high functional lifespan due to good contamination control and monitoring properties.
5. Make sure the fluid complies with industry-specific requirements, such as environmental considerations and fire resistance.

Specialty Fluids

Specialty hydraulic systems require specialty fluids. Along with general hydraulic fluids, you’ll find these options on the market for specific applications:

• Anti-wear oils
• Biodegradable oils
• Energy-efficient oils
• Environmentally friendly oils
• Fire-resistant oils
• Food grade oils
• Low-temperature or cold-temperature options
• Marine oils

Hydraulic Oil Experts

At Lubrication Engineers, we can help identify the needs of your hydraulic system and determine the right fluid for long-term optimal performance. Contact us today to learn more about our selection and services.

Different Types of Lubrication

What are lubricants? Lubricants minimize the friction that occurs when two parts come into contact. They can also lessen or prevent oxidation and corrosion, create a seal that safeguards against dirt and dust, serve as power transmission, and regulate heat in certain applications.

Four types of lubricants are prevalent in commercial and industrial applications: oil, grease, and penetrating or dry lubricants. Understanding these types and when they should be used or not used will help you choose the ideal one for your application.

Oil

Oil is a thin lubricant available in multiple viscosities, or weights. A low-weight oil is thinner, while a high-weight one is more viscous. Oil-based lubricants contain additives to either enhance or suppress specific characteristics inherent to the oil. Oil type and its application will dictate the necessary additive amount, such as dispersant in engine oil. The base for oils comes in mineral, vegetable and synthetic varieties, or a mixture of any of the three, to offer different properties. Biodegradable or low-toxicity oils are preferable for their environmental safety, whereas synthetic versions are ideal for extreme conditions.

When to Use Oil

Oil lubricants provide low-resistance lubrication compared to grease. They’re suitable for tasks like blade sharpening and bearing or hinge applications.

When Not to Use Oil

Oil isn’t suitable for wet, dusty or otherwise dirty surfaces. When oil combines with contaminants like dirt, it can increase friction rather than decrease it, and the oil lubricant can gum up. Oil can also absorb water when applied to a wet surface, causing the lubricant to lose adhesion to the part or component that you’re lubricating and wash away.

Grease

Grease is an oil-based lubricant with additives and thickening agents to increase its self-lubricating properties. These might include molybdenum disulfide, graphite, polytetrafluoroethylene (PTFE) or other solid particles. The lubricant provides a stickiness that helps it adhere to surfaces, protecting them from damage and corrosive degradation.

When to Use Grease

Grease is an ideal substitute for oil when oil’s enhanced cooling properties are not necessary. Grease is suitable for linkages, chains, bearings and gears, particularly when you require stickiness to adhere a lubricant to the surface for an extensive time frame. Grease can also provide sealing protection against moisture and dust.

When Not to Use Grease

Grease isn’t suitable for lubricating fine or fast-moving machinery parts as it could actually create resistance or slow down the machinery’s operations.

Penetrating Lubricants

When removing a rusty part like a bolt or nut, a penetrating lubricant can loosen even years’ worth of corrosion or debris. Penetrating lubricants enter tiny surface cracks and crevices on a metal part to break down rust. They’re also suitable for wire ropes, as the evaporative solvent in penetrating lubricants enhances the lubricant’s migration into the rope’s core. The lubricant evaporates, leaving behind a protective lubricating film on each wire rope strand.

When to Use Penetrating Lubricants

Penetrating lubricants are ideal for warehouse repair and maintenance tasks, such as loosening nuts and bolts. They’re also suitable for lubricating cables, chains and wire ropes.

When Not to Use Penetrating Lubricants

Penetrating lubricants are only suitable for certain tasks and can’t replace other lubricants in their ideal applications.

Dry Lubricants

Dry lubricants are composed of self-lubricating materials in tiny particles, including molybdenum disulfide, graphite and PTFE. Users often mix these dry particles with fluids like solvents, alcohol or water and apply them as a spray. The liquid mixer will evaporate over time, leaving behind a slick, microscopic surface film that provides effective part lubrication.

When to Use Dry Lubricants

Dry lubricants are the optimal choice to lubricate machine components that must perform at high-precision levels. They keep a part’s surface clean and don’t cause gunk build-up like grease. These lubricants can also withstand extremely high temperatures and pressure that would oxidize oils.

Applications include:

• Actuating ball and lead screws
• Gears
• Hinges
• Bearings
• Locks
• Threaded rods

When Not to Use Dry Lubricants

Fluids can wash away dry lubricants, so you shouldn’t use this type in applications where the part’s surface may be exposed to solvents or liquids.

Specialty Lubricants

Certain applications rely on specialty lubricants for their unique properties.

Gear Oils

Gear oils safeguard gear teeth and the gears themselves against wear and abrasion. They offer thermal stability to keep sludge from building up on these components.

Compressor Oils

Compressor oils provide lubrication for rotating compressor parts to lessen or eliminate friction. They also transfer heat from the compressor to cool it during air compression and help seal the compression chamber.

Solid Bar Lubricants

Solid bar varieties lubricate components within rotary dryers and kilns to maintain proper operation and reduce wear that can cause misalignment and refractory loss. The lubricant goes in a kiln between the shell and tire bore, coating the bore in a protective film.

Learn More With Lubrication Engineers

Lubricants are available for virtually every application, providing lubrication, protection, sealant and heat transfer, as needed. Choosing the ideal lubricant for your application is essential to prevent premature part or machinery failure. Lubrication Engineers partners with companies worldwide, providing reliable lubrication solutions since 1951. Our expert staff formulates and produces LE lubricants with proprietary additives in-house to ensure high-quality products. We also offer comprehensive services including oil analysis, audits, assessments, and training.

Contact us to learn more about our lubrication solutions, or request a lubricant recommendation today.

Causes of Low Oil Pressure in Engines

Low oil pressure in an engine can disrupt performance, lead to overheating and friction between moving parts, and eventually cause the engine to stall. Learning more about the common causes of low oil pressure in different environments can help you protect your engines from damage – and reduce the risk of costly repairs and replacement.

Learn more about why maintaining proper oil pressure levels is important and what can cause low oil pressure in vehicles.

Why Oil Pressure Is Important

While many factors determine the lifespan of an engine and how well it performs, having the right oil pressure is one of the most important. Engines have a lot of moving parts and can generate a lot of heat. These moving parts require sufficient lubrication to eliminate the risk of premature wear and to keep engine temperatures in an appropriate range.

However, it’s not enough to just supply the engine with oil; that oil must also be at sufficiently high pressure to coat all the moving parts of the system. Once there’s not enough pressure, the oil won’t reach all the surfaces, leading to metal-on-metal contact, damaging friction and high temperatures. Left untreated, low oil pressure levels can also break seals in the engine and cause significant damage to other components.

Vehicle operators and maintenance technicians can stay on top of potential oil pressure issues with regular inspections and maintenance. Vehicles have a pressure gauge that automatically monitors pressure levels and turns on an indicator light as soon as oil pressure drops, at which point drivers should immediately halt the vehicle and resolve the issue before continuing to drive.

What Causes Low Oil Pressure?

You can troubleshoot each of the four common underlying causes of low oil pressure to discover which is to blame.

Not Enough Oil in the Engine

Oil needs to be regularly replaced and replenished to keep vehicles running smoothly. Some of the reasons why oil levels can decrease over time include:

• Leaks in the oil plug or seals
• Evaporation, causing faster-than-normal oil consumption
• Burning, due to worn piston rings

Adhere to a strict oil replacement schedule and regularly assess oil levels to prevent this cause of low oil pressure. As engines age, their oil consumption naturally increases, so it is normal to refill more often as time goes on. However, make sure there are also no oil drops or leaks evident on the ground below the vehicle, as this indicates leaking components that must be fixed.

Too High or Low Viscosity

Oil comes in many different viscosity levels, which determine how easily it will flow throughout an engine at certain temperatures. Different vehicles will require different types of oil, so the vehicle’s manual will say the manufacturer’s recommended oil viscosity rating and grade. In general, high-viscosity oil is thicker and produces more resistance, while low-viscosity oil is thinner with less resistance. High-viscosity oil is typically used in summer months or warmer temperatures, while low-viscosity oil is used in colder temperatures.

If the wrong oil viscosity is used, the engine may register it as low oil pressure even though the oil has been properly replenished. The best way to prevent this potential cause is to double-check that the right oil is being used for the specific make and model of the vehicle (and the season or climate at hand). Mechanics should also be able to confirm which oil they used if the vehicle was taken to a shop for an oil change.

Engine Wear

Sometimes, the underlying cause is engine damage. First, check the dipstick to rule out the possibility that the wrong type of oil or oil level is being used. If both are correct, the low oil pressure warning could be indicating that components of the engine itself are worn. Engine bearings can wear down if the vehicle operates at high speeds. Older, frequently used cars will experience engine wear more quickly.

To address this potential cause, a trained mechanic should inspect the engine for signs of wear. Regular maintenance can also reduce the risk of engine wear.

Defective Oil Pressure Gauge

If you’ve already checked for all of the above potential causes and the low oil pressure light is still on, it may be a sign that the oil pressure sensor itself is defective. If, even after replacing the sensor, the low oil pressure warning still comes on, it could be due to a faulty oil pump.

Industries Where Lubricants Are Most Affected by Cold Weather

Some industries need to store and use lubricants outside, where cold temperatures can negatively impact their effectiveness. This commonly applies to the mining, agriculture, transportation, oil and gas, and water treatment industries.

Freezing temperatures increase the viscosity of oil-based fuels and lubricants. While they don’t freeze solid, they become thicker until they resemble wax. Under 15°F (-9°C), the wax in the lubricant or oil starts to crystallize, separating from the oil. In this state, it is very difficult to remove the oil from the container.

Insulating fuel pipes that carry fuel oils can mitigate the risk of freezing, separating and clogging. It’s also helpful to know the freezing temperatures for different gear oils, motor oils and hydraulic oils. Thin motor oils like 10W30 varieties start to thicken at 50°F (10°C) and will freeze at -20°F (-29°C), while hydraulic and gear oils freeze at -10°F (-23°C). But higher-viscosity oils like 15W30 are designed to stay fluid until temperatures drop to -55°F (-48°C).

Turn to Lubrication Engineers to Learn More About Engine Oils

The team at Lubrication Engineers is here to help our customers with information about engine oils and expert guidance in keeping systems in good repair. Learn more about engine oils so you can protect your vehicles and industrial systems.