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Comprehensive Guide to R&O Additives
HiTEC® Industrial Additives
Afton Chemical is a global leader in petroleum additives, producing world-class solutions for the industrial lubricant market. Afton's HiTEC® rust and oxidation (R&O) additives are designed for blending across a range of base oils, specifications, and performance tiers, providing formulation flexibility and inventory consolidation. These ashless R&O additive packages extend the life of circulating systems, improving operating efficiency and reducing lifecycle costs.
R&O additives are critical components of industrial lubricants exposed to moisture, high temperatures, or corrosive environments. This guide covers how these rust and oxidation additives work, where they are used, and how to select the right package, and it highlights Afton Chemical’s HiTEC® solutions for R&O industrial oils.
Core benefits of these rust and oxidation additives include extended drain intervals, cleaner systems with reduced varnish and sludge, lower wear from corrosion control, improved foam control and air release when paired with antifoam agents, and consistent viscosity from strong oxidative stability.
Compared with other lubricant types, R&O oils prioritize corrosion and oxidation resistance without heavy extreme-pressure chemistry. Versus anti-wear (AW) hydraulic oils, R&O fluids typically contain lower levels of zinc or other anti-wear agents and target lightly loaded bearings and turbines. Versus extreme-pressure (EP) gear oils, they omit high-sulfur/phosphorus chemistries intended for severe sliding. This makes R&O formulations ideal for turbines, circulating systems, compressors, paper machines, and lightly loaded gear and bearing applications where cleanliness and stability are paramount.
Understanding R&O Additives
R&O additives are multicomponent packages that prevent moisture-driven corrosion on metal surfaces and slow oxidative degradation of base oils—key drivers of varnish, sludge, and viscosity increase. Their primary role is to extend service life and protect equipment in systems operating under moderate loads and stable temperatures.Core benefits of these rust and oxidation additives include extended drain intervals, cleaner systems with reduced varnish and sludge, lower wear from corrosion control, improved foam control and air release when paired with antifoam agents, and consistent viscosity from strong oxidative stability.
Compared with other lubricant types, R&O oils prioritize corrosion and oxidation resistance without heavy extreme-pressure chemistry. Versus anti-wear (AW) hydraulic oils, R&O fluids typically contain lower levels of zinc or other anti-wear agents and target lightly loaded bearings and turbines. Versus extreme-pressure (EP) gear oils, they omit high-sulfur/phosphorus chemistries intended for severe sliding. This makes R&O formulations ideal for turbines, circulating systems, compressors, paper machines, and lightly loaded gear and bearing applications where cleanliness and stability are paramount.
R&O Additive Components
While R&O additive packages typically account for a small percentage of the total lubricant formulation (often less than 1% by weight), they significantly impact the fluid's final performance. These are the common components and the role they play in the formulation:
Rust Inhibitors
Form hydrophobic films to block water-induced corrosion
Oxidation Inhibitors
Phenolic and aminic antioxidants interrupt free radical chains and slow thermal and oxidative breakdown
Metal Deactivators
Additives, such as benzotriazole derivatives, passivate copper and other catalytic metals
Demulsifiers
Promote rapid water separation to reduce rust and ease dehydration
Antifoam Agents
Often silicone-based, these agents reduce foam and improve air release
Friction Modifiers
Reduce metal-to-metal contact to prevent wear
Together, these components stabilize the base oil under heat and oxygen exposure, protect surfaces from water and acidic byproducts, improve filterability and contaminant separability, and limit deposit formation that can impair valves and bearings.
Common Applications
The following lubricant applications benefit from excellent rust protection, strong water separability, low varnish tendency, and dependable air release from modern R&O and circulating oil additives:
Turbine oils for steam, gas, and hydro turbines
Circulating oils for paper machines and metal processing
Compressor and vacuum pump oils where deposit control is critical
Lightly loaded gearboxes and bearings under moderate conditions
Hydraulic systems without heavy AW/EP
Heat transfer and quench oils requiring oxidation control and cleanliness
Selecting the Right R&O Additives
When selecting an R&O additive for your formulation, best practices include matching the additive chemistry to the base oil and viscosity grade, considering the application and severity of the operation, and accounting for key methods and approvals.Different base oils will have varying antioxidant responses and additive compatibilities. Operating conditions, such as temperature, air release, water ingress, and system metallurgy, will impact oxidation rates, demulsibility targets, foaming tendency, and copper passivation needs. High deposit control and filterability goals may require a higher-performing additive package.
Approvals heavily influence additive choices. Turbine OEMs have specifications that define performance criteria that lubricant marketers use to ensure compatibility, reliability, and safety in turbine systems. Common OEM turbine approvals include GEK 32568/107395, Siemens TLV/T, Alstom HTD 90117V, and MAN Turbo. In addition to OEM specifications, look for performance against key methods and approvals, such as ASTM D4304 (steam and gas turbines), ASTM D943 (TOST), ASTM D4310 and D7843 (varnish/insolubles), ASTM D1401 (water separability), ASTM D892 and D6082 (foam), and ASTM D665 and D1748 (rust). Meeting these benchmarks indicates robust rust and oxidation protection.
Choosing the right R&O additive can be challenging and may involve lengthy qualification and testing. ChemPoint and Afton have technical specialists available to assist you in this process. Contact us today to speak with a technical representative.
Afton Chemical HiTEC® Portfolio
Circulating Oil Additive Packages
Grade
|
Base Oils
|
Description
|
|---|---|---|
Group I
|
Scalable treat rate with performance approvals for circulating oils
|
|
Group I
|
Scalable treat rate with performance approvals for circulating oils
|
|
Group I
|
Cost-effective additive for circulating and bearing oils
|
Turbine Oil Additive Packages
Grade
|
Base Oils
|
Description
|
|---|---|---|
Groups II & III
|
Scalable treat rate for best-in-class sludge and varnish control for top-tier turbine oils | |
Groups II & III
|
Enhanced oxidation protection for top-tier steam and gas turbine oils | |
HiTEC® 1505
|
Groups II & III
|
Meets key OEM approvals for mainstream turbine oils using geared systems |
Groups I, II, & III
|
Scalable treat rate with performance approvals for entry-tier and mainstream turbine oils |
|
Groups II & III
|
Scalable treat rate with performance approvals for mainstream turbine oils |
Compressor Oil Additive Packages
Grade
|
Base Oils
|
Description
|
|---|---|---|
Group III
|
Exceptional oxidation and thermal stability for high-performance compressor oils
|
|
Group III & Synthetic
|
Enhanced demulsification performance for mainstream compressor oils and synthetic formulations
|
|
Group II
|
Scalable treat rate with performance approvals for mainstream compressor oils
|
|
Group II
|
Scalable treat rate with performance approvals for mainstream compressor oils
|
|
Group II
|
Anti-wear hydraulic additive with application in compressor oil formulations that require added wear protection
|
Availability, treat rates, and approvals vary by region and formulation. Contact ChemPoint for current datasheets, OEM approvals, and recommendations tailored to your base oil preference, operating conditions, and needs.
HiTEC® is a registered trademark of Afton Chemical Corporation.
What Are R&O Additives?
R&O additives are chemical components added to lubricant formulations to prevent rust and oxidation, enhancing fluid stability and protecting metal surfaces.
What Is in an R&O Additive Package?
R&O additive packages mainly consist of antioxidants, corrosion inhibitors, metal passivators, and diluent oil. Some packages may include other components, such as demulsifiers, friction modifiers, antifoam agents, and anti-wear agents for high-load applications.
Why Are R&O Additives Important in Lubricant Formulations?
R&O additives extend the service life of industrial lubricants, protect machinery from wear and corrosion, and ensure efficient system operations.
How Are R&O Additives Evaluated?
R&O additives are typically assessed through standardized tests that evaluate thermooxidative stability, protection of the metal surface, and surface characteristics, such as demulsibility and foam.
What Formulations Commonly Include R&O Additives?
R&O additives are often formulated into circulating and bearing oils, compressor oils, turbine oils, and hydraulic fluid and gear oils that do not require high-load resistance or wear protection.
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