A Buyer’s Guide to Mobil HyJet Aviation Hydraulic Fluids
At the heart of most modern aircraft, especially tactical or large aircraft, is the hydraulic system. The hydraulic systems operate landing gears, steering systems, brakes, and large flight control surfaces, including flaps, leading-edge flaps, spoilers, slats, rudders, and more.
At its core, the most important component of a reliable hydraulic system is the hydraulic fluid. Hydraulic fluid that stays clean, that resists fire, and remains fluid in all temperature swings keeps hydraulic systems running smoothly for decades.
For over four decades, Greenwood Aerospace has been a key supplier of high-performance consumables to federal agencies (FAA, USDA, etc.), defense contractors, and military maintenance teams.
We are on the GSA Schedule now as part of our initiative to streamline procurement of critical infrastructure items for aviation maintenance and flight operations for our federal partners, so you can easily source and procure hundreds of items on GSA Advantage with a government charge card.
This series focuses on the Mobil HyJet line of hydraulic fluid to help government buyers, maintainers, and fleet managers understand the key differences between HyJet IV-Aplus and HyJet V, along with related product data and procurement pathways. Be sure to check out our companion pieces on Mobil HyJet IV-Aplus, Mobil HyJet V, and Mobil Hydraulic Fluid Packaging Options for a deeper look at each specification.
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Why Fire-Resistant Hydraulic Fluids Are Critical in Aviation
The standard operating pressure for modern aircraft is 3,000 psi, with some outliers reaching 4,000 psi. Conventional mineral-oil fluids can ignite when exposed to high-temperature components, making fire-resistant phosphate-ester fluids the obvious choice for safety.
These fluids are designed to perform two seemingly opposite tasks: flow easily at sub-zero temperatures while maintaining lubricity and viscosity when system temperatures exceed 300°F. It also had to resist oxidation, corrosion, and moisture contamination and remain compatible with all common seals, hoses, and elastomers used on the aircraft around hydraulic systems.
Military and commercial aircraft that use hydraulic systems (which are most of them) commonly rely on phosphate-ester hydraulic fluids for mission-critical systems, including
- Landing-gear actuation and steering assemblies
- Primary and secondary flight-control systems
- Cargo doors and thrust-reverser actuation
- Braking systems
Hydraulic system failures compromise the integrity of all systems, and subpar or incorrect hydraulic fluid can cause them. Mobil HyJet hydraulic fluids are engineered for just this purpose.
About SAE AS1241: Types IV and V
The governing specification for modern fire-resistant hydraulic fluids is SAE Aerospace Standard AS1241. It defines performance requirements for phosphate-ester fluids used in aircraft hydraulic systems.
Within that standard, two designations dominate today’s fleets: Type IV and Type V.
Type IV: Traditional Performance with Proven Reliability
Type IV fluids such as Mobil HyJet IV-Aplus meet SAE AS1241C and provide excellent low-temperature flow and deposit control. They are approved by Airbus, Boeing, Embraer, and ATR for use across wide-body, regional, and business aircraft. Type IV remains common in legacy platforms and mixed fleets where system materials and seals are already validated to this chemistry.
Type V: Next-Generation Thermal Stability
Type V fluids, such as Mobil HyJet V, represent the evolution of phosphate-ester technology. They exhibit higher oxidation stability, improved corrosion protection, and broader compatibility with modern elastomers. Type V fluids are specified in newer Boeing and Airbus models and increasingly in business-jet and military transports that operate at higher hydraulic-system temperatures.
Understanding the difference ensures maintenance planners and procurement teams select the correct fluid when transitioning aircraft or managing mixed fleets.
Mobil HyJet Product Line Overview
ExxonMobil’s HyJet family of products covers Type IV and Type V requirements. You will have a direct replacement for almost every approved phosphate-ester fluid in service.
Mobil HyJet IV-A plus
A top-performing Type IV fluid that meets SAE AS1241C and numerous OEM specifications:
- Airbus NSA 307110N
- Boeing BMS 3-11P Type IV, Grades B and C
- Douglas DMS 2014H Type 4
- Embraer and ATR NSA 307110N
Its low-temperature viscosity and excellent deposit control minimize valve sticking and filter blockage. The formulation’s additive package reduces acid formation and varnish, keeping hydraulic components clean and responsive even after thousands of operating hours.
Mobil HyJet V
A Type V phosphate-ester fluid formulated for extreme thermal and oxidative stability. It exceeds SAE AS1241 Type V, Boeing BMS 3-11P Type V Grades A and C, Airbus NSA 307110N Type V, and Gulfstream 1159SCH302J Type V requirements.
Mobil HyJet V is ideal for newer aircraft with compact, high-pressure hydraulic systems. The fluid’s improved corrosion and wear protection extends pump and actuator life while maintaining consistent viscosity at both high and low temperatures.
Both products share the same commitment to extended service intervals, material compatibility, and low-maintenance reliability, supported by ExxonMobil’s extensive qualification data.
Packaging Options for Commercial and Military Procurement
Our goal from the start was to make all of these products more accessible to military units and federal flight operations, where logistics are notoriously slow to get started and often hard to procure. With GSA Advantage, it is just a click away.
We offer HyJet hydraulic fluids to federal buyers in several formats.
Mobil HyJet IV-A Plus & Mobil HyJet
- All of these are available directly from GSA Advantage for immediate sale and delivery. You can follow the hyperlinks above, and they will take you directly to the referenced item.
Compliance and Cross-Platform Compatibility
Mobil HyJet fluids are approved for use on dozens of aircraft by all major manufacturers. It meets the following standards, which cover thousands of aircraft the world over:
- SAE AS1241 Type IV / Type V
- Boeing BMS 3-11P Grades A, B, C
- Airbus NSA 307110N
- Douglas DMS 2014H Types 4 and 5
Since both are phosphate-ester-based fluids, they can be interchanged during OEM-approved changeovers. Make sure to check your technical library for conversion procedures and confirm that the fluids are correct if there are any questions.
How to Buy Mobil HyJet Fluids Through GSA Advantage
The process of ordering Mobil HyJet hydraulic fluids from Greenwood Aerospace is intentionally simple. We stock several variations of both products, ready to go via GSA Advantage. Government buyers can search by NSN, SKU, or product name and order directly from the listing.
Of course, we also link to the products in the article to save you time.
Greenwood Aerospace is a Native American-owned, HUBZone-certified small business headquartered in the heart of the United States. The company provides rapid fulfillment, contract compliance support, and bulk-order pricing tailored to government customers.
Contact Information
You can reach us the following ways:
Email: gsasales@greenwood.aero Phone: 580-865-6000 or 833-GSA-EBUY (833-472-3289)
You can reach out to us directly through these communication channels. For any questions, expedited delivery requests, large order inquiries, or to confirm product availability, contact us at the information above.
Parting Thoughts
Greenwood Aerospace has been a trusted name in government procurement for over four decades. We have worked with every military branch and numerous federal agencies over the years, successfully fulfilling hundreds of contracts.
In addition to ExxonMobil products, we carry dozens of leading brands and have nearly 1,000 items on GSA Advantage, with more being added regularly. You can check out our profile on the GSA eLibrary and our price list for current prices on all products. The products in question are always linked in our articles for your convenience.
This article is part of the Greenwood Aerospace Mobil HyJet Series, designed to help procurement teams and maintainers make informed decisions about Mobil HyJet IV-A Plus and Mobil HyJet V hydraulic fluids. Explore the complete lineup in our Ultimate Guide to Mobil HyJet Aviation Hydraulic Fluids.
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