Why Use of Zinc-Free Hydraulic Fluids is on the Rise
Key Highlights
- Growing awareness about the environmental impacts of zinc and stricter regulations are helping accelerate the shift toward zinc-free hydraulic fluids in various industries.
- Improvements in additive chemistries is aiding uptake of zinc-free options by enabling them to match or surpass the performance of traditional zinc-based formulas.
- Zinc-free hydraulic fluids offer additional advantages such as oxidation stability and reduced sludge formation which is also helping to make them a preferred choice in many applications.
Zinc is often used in hydraulic fluids and other lubricants because of its ability to resist wear and oxidation. However, as the environmental impacts of zinc have become more evident, development and use of zinc-free options is increasing.
Among the drawbacks of zinc is the fact it is not biodegradable. This means that if a system leaks and its hydraulic fluid gets into the ground or waterways, it will stay there for years where it can potentially harm wildlife, plants and humans.
Josh Dickstein, Ph.D., Technology Development Manager, and Ryan Konrad, Technology Deployment Manager, at Lubrizol, anticipate rising adoption of zinc-free fluids and additives in the coming years. Continued technological advancements for these formulations, sustainability initiatives, and regulations will all help drive their increased use.
In this Q&A with Power & Motion, Dickstein and Konrad highlight the applications where they see zinc-free options being used most, ongoing development challenges and potential solutions for these fluids as well as benefits they can provide beyond reduced environmental impact.
*Editor’s note: Questions and responses have been edited for clarity.
Power & Motion: What is the current state of the zinc-free additives and hydraulic fluids market? Are you seeing demand increase for zinc-free options? If so, what is driving this demand?
Josh Dickstein and Ryan Konrad: Yes, there is a noticeable increase in demand for zinc-free options, especially in the lubricant additives. The main drivers for this demand include:
- Environmental Considerations – Growing awareness about the environmental impact of zinc, particularly zinc dialkyldithiophosphate (ZDDP), which is commonly used in lubricants, are pushing manufacturers to seek zinc-free alternatives.
- Wastewater Treatment Constraints – Industrial facilities are facing stricter wastewater discharge limits for metals, including zinc. This is motivating companies to reformulate products to reduce or eliminate zinc content.
- Sustainability Initiatives – End-users and manufacturers are increasingly adopting sustainability targets, leading to greater interest in environmentally friendly and bio-based lubricants and additives, which often avoid the use of zinc.
- Industry Specifications – Some OEMs and industry standards [organizations] are developing zinc-free hydraulic requirements.
Power & Motion: Are there particular applications or industries where demand for zinc-free is strongest?
Josh Dickstein and Ryan Konrad: Demand for zinc-free options is strongest in [three] specific applications and industries.
- Hydraulic Fluids – Many industrial hydraulic systems, especially those used in environmentally sensitive areas (such as mining, forestry, construction and marine operations), are moving toward zinc-free hydraulic fluids. This shift is in part driven by environmental regulations and concerns about zinc contamination in water systems.
- Marine and Offshore Industries – These industries face stringent regulations to prevent water pollution, leading to increased demand for zinc-free lubricants in engines and machinery operating near or on water.
- Food-Grade and Biodegradable Lubricants – Applications where lubricants may come into contact with food or are required to be biodegradable (e.g., agriculture, food processing) often specify zinc-free formulations to meet health and safety standards.
Power & Motion: How have you seen the zinc-free market progress from a technology standpoint in recent years?
Josh Dickstein and Ryan Konrad: The zinc-free market has made significant technological progress in recent years, particularly in the development and commercialization of high-performance additives for lubricants and fluids.
Improved Additive Chemistries
Ashless and Non-Metallic Additives – Formulators have developed sophisticated ashless (zinc-free) anti-wear and antioxidant components, and novel phosphorus-based anti-wear components, which can match or even surpass the performance of traditional ZDDP additives in specific end uses.
Enhanced Oxidation and Wear Protection
The latest zinc-free solutions can demonstrate improved resistance to oxidation and comparable wear protection, helping to extend equipment life and oil drain intervals to levels comparable to, or better than, zinc-based formulations. Relevant testing to demonstrate oxidation performance include ASTM D943 TOST or the JCMAS P045 A2F10 pump test.
Response to Regulations
Innovation has accelerated in response to awareness of environmental and health impacts of lubricants of all types, leading to more zinc-free hydraulic fluids that can handle a variety of demanding applications.
Power & Motion: What are some of the challenges associated with developing zinc-free additives/hydraulic fluids, and how can these be overcome?
Josh Dickstein and Ryan Konrad: Developing zinc-free additives and hydraulic fluids presents several technical and application-related challenges. These can be broken into four main challenges, followed by strategies to overcome them.
Challenge #1 - Achieving Equivalent Performance to ZDDP
ZDDP has long been valued for its excellent anti-wear and antioxidant properties at a low treat rate and overall formulation cost. Replicating this performance with zinc-free formulations while also balancing total formulation cost is a continual challenge.
As the lubricant industry moves to higher quality base oils, there has also been a corresponding shift that has enabled the use of zinc-free hydraulic additives. Zinc-free hydraulic products are typically perceived to be a higher market tier and therefore are often used in combination with better quality base oils such as API group II, III, and IV. In comparison, many legacy zinc-containing hydraulic products have been formulated with group I base oil considerations in mind.
The Solution: Extensive laboratory and field testing to optimize formulations for specific applications. Development of new phosphorus-based anti-wear components to replace ZDDP has been one formulation approach.
Challenge #2 - Oxidation Stability
Zinc-free fluids may be more prone to oxidation, leading to sludge and acid formation, which can reduce lubricant life and equipment reliability.
The Solution: Incorporation of high-performance zinc-free antioxidants and anti-wear components to boost oxidation resistance. Use of better quality base oils (such as Group II, III, and synthetic oils) that are inherently more resistant to oxidation.
Challenge #3 - Cost and Availability of Alternatives
Some zinc-free additive components can be more expensive or less readily available than traditional ZDDP, impacting the overall cost and supply chain reliability.
The Solution: Ongoing R&D investment to commercialize cost-effective alternatives and scale up production. Collaboration with suppliers to ensure consistent supply and cost management.
Challenge #4 - Meeting Diverse Regulatory and Market Needs
Regulations and customer requirements can vary widely by region and application, making universal solutions difficult.
The Solution: Developing additive packages to address specific regional, industry, and environmental needs. Close engagement with regulatory bodies and end-users during development and validation.
Power & Motion: What further developments are necessary in the market?
Josh Dickstein and Ryan Konrad: Several key developments are still necessary for zinc-free hydraulic fluids to reach their full potential and broader market adoption, which can be divided into four key areas:
1. Enhanced Anti-Wear and Oxidation Stability – Zinc-free fluids must consistently deliver anti-wear and oxidation protection equal to or better than traditional zinc-based formulations, particularly in high-pressure and high-temperature environments. Continued innovation in additive chemistry is needed to further close any remaining performance gaps.
2. Cost Effectiveness – Zinc-free solutions must become more cost competitive with traditional products to facilitate wider adoption, especially in cost-sensitive markets. Economies of scale, new manufacturing processes, and sourcing less-expensive raw materials will help reduce costs.
3. Sustainability and Biodegradability – As environmental regulations evolve, there’s a growing demand for not only zinc-free but also biodegradable and sustainable hydraulic fluids. This will require synergistic development of zinc-free and environmentally acceptable lubricants (EALs) using renewable base oils and eco-friendly additives.
4. Education and Awareness – End-users and maintenance professionals may not be fully aware of the benefits or best practices for using zinc-free fluids. Increased training, technical support, and dissemination of field performance data will support the transition.
Power & Motion: Besides environmental benefits, are there other advantages to using zinc-free fluids?
Josh Dickstein and Ryan Konrad: Yes, besides environmental benefits, there are several other advantages to using zinc-free hydraulic fluids, including:
- Reduced Sludge and Deposit Formation
- Improved System Performance
- Oxidation Stability
- Broader Application Range
- Suitability for Sensitive Environments.
Without zinc, there is less risk of forming certain types of deposits or varnish that can clog filters and narrow passages in hydraulic systems, leading to improved system cleanliness and reliability.
Modern zinc-free fluids can provide equal or better resistance to oxidation compared to traditional zinc-containing fluids. This results in longer fluid life and reduced maintenance intervals.
Zinc-free fluids can be preferred in sensitive environments due to perceived health and environmental benefits and compatibility with some environmental regulations.
Power & Motion: How do you see uptake of zinc-free options progressing in the coming years? What factors do you see driving demand going forward?
Josh Dickstein and Ryan Konrad: The uptake of zinc-free hydraulic options is expected to continue growing steadily in the coming years, with several key factors driving increased demand and adoption.
- Stricter Environmental Regulations – Regulatory bodies worldwide are imposing tighter environmental restrictions. Industries are proactively transitioning to zinc-free fluids to ensure compliance with current and future regulations, especially in ecologically sensitive sectors like marine, mining, and municipal operations.
- Advancements in Additive Technology – Ongoing improvements in zinc-free additive chemistry are closing the performance gap with traditional zinc-based fluids. As performance, oxidation stability, and wear protection improve, more industries will view zinc-free fluids as viable or even preferable alternatives.
- Sustainability Initiatives – Companies and public institutions are increasingly prioritizing sustainability, including the use of environmentally friendly and biodegradable lubricants. Zinc-free fluids are often part of broader sustainability strategies, further driving demand.
- Expansion Into New Applications – As zinc-free formulations become more widely accepted, they are being adopted in a wider range of applications. This broadens their market base and drives overall uptake.
The market outlook for zinc-free hydraulic fluids and additives is positive. In the short-term, continued growth is expected, especially in regions with stringent environmental rules and in industries with high regulatory oversight.
As component and formulation costs decrease and performance increases, zinc-free fluids could become the new norm for many hydraulic applications, prompting mid- to long-term growth.
It is important to note that the market has been accepting of zinc-free hydraulic additives that are similar but different from completely ashless technologies. In short, some metals (including Calcium or Magnesium from related metal-containing components such as detergents or dispersants) can be included in zinc-free fluids. This is in part to help address performance with completely ashless technologies that can experience electrostatic discharge causing hardware damage under certain conditions such as high flow rates and fine filtration.
Zinc-free and ashless hydraulic products currently account for approximately 10% of the global hydraulic market with the exception of the Japanese hydraulic market where it accounts for the majority of hydraulic fluids that are used. The global market share of zinc-free hydraulic fluids is expected to slowly expand over time.
About the Author
Sara Jensen
Executive Editor, Power & Motion
Sara Jensen is executive editor of Power & Motion, directing expanded coverage into the modern fluid power space, as well as mechatronic and smart technologies. She has over 15 years of publishing experience. Prior to Power & Motion she spent 11 years with a trade publication for engineers of heavy-duty equipment, the last 3 of which were as the editor and brand lead. Over the course of her time in the B2B industry, Sara has gained an extensive knowledge of various heavy-duty equipment industries — including construction, agriculture, mining and on-road trucks —along with the systems and market trends which impact them such as fluid power and electronic motion control technologies.
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