Get background on common issues that aviation professionals face in their everyday operations.
Find answers to the most commonly asked questions about ExxonMobil aviation products and services.
Get background on common issues that aviation professionals face in their everyday operations.
Explore details on Mobil Jet™ oils — designed to meet today and tomorrow’s aviation challenges.
Discover best practices and recommendations for our series of Mobil™ HyJet™ hydraulic fluids.
Find insights on using our multipurpose airframe and wheel bearing greases and gear oils.
Here is a brief list of common industry terminology:
|Auxiliary Power Unit
|Constant Speed Drive
|Integrated Drive Generator
|Time Between Overhaul
|Mean Time Between Failures
|Mean Time Between Removals
|Specific Fuel Consumption
|Exhaust Gas Temperature
|Extended Twin-engine Operations
The shelf life on an aviation lubricant product is listed on the container/package as the “Use by” date. In the event that the package/container does not have a “Use by” date, check the manufacturing date list in the Certificate of Analysis (COA) and add the recommended shelf life. For information on recommended shelf life, please refer to the COA (shelf life referenced on bottom of the page), or the ExxonMobil Aviation Shelf Life Bulletin.
Jet oils are lubricants developed specifically for aviation gas turbine engines. Jet oils are designed to operate over an extreme temperature range. Temperatures can range from -40 degrees Celsius for cold starting at high altitudes and go up to 250 C for bearing lubrication. Jet oils can also be used to lubricate certain land-based and marine engines (aviation derivatives) typically used for power generation or propulsion aboard seagoing vessels.
Mobil Jet oils are compatible with the materials provided under normal conditions of jet engine operation. For compounds and components (e.g., plastics) not typically used in aviation engines, compatibility studies must be run. Even with elastomers, great care must be exercised when applying data from one study to another. Unique circumstances could result in a response that is different from that predicted in a study. Elastomers, like lubricants, have many and varied formulations, all of which may not react in a similar fashion under the same conditions. Consequently, each situation/application must be evaluated separately.
The biggest difference is that land based installations do not have the benefit of ram air cooling and therefore the reservoirs typically are larger (500+ gallons versus 6 gallons) in order to provide sufficient residence time for oil cooling. Additionally, many land-based turbines are run intermittently for peak electrical or gas compression periods, as opposed to every day as in the case of aircraft engines. All of this results in the potential for a higher possibility of acid formation due to buildup of moisture/water in the lubricant. As such, many equipment manufactures recommend reservoir drain and flush service intervals to ensure continued oil performance. It should be noted that while the larger reservoir systems provide for oil cooling, the internal engine temperatures are every bit as severe as those seen in an aircraft engine. Therefore the need for good thermal stability is still a critical performance feature of synthetic jet turbine lubricants used in land-based applications.
First, always consult with the engine/equipment builder recommendations prior to enacting the changeover to ensure compliance. Next, we recommend converting systems by simply "topping-off" the system with the new oil. This approach allows the original brand of oil to be phased out gradually over time as more "top-offs" occur. The standard "drain and fill" method is less desirable because there is the potential for disturbing system equilibrium (e.g., seal swell/compatibility, deposit loosening/washing, etc). Since oil is consumed in a jet engine on a regular basis (average - 0.20-0.80 quarts/hr), estimates indicate the oil system will typically contain more than 95 percent of the new oil in a few hundred hours of operation.
Yes, they are compatible. The oil approval process includes compatibility testing for all jet oils. Approval requirements mandate that jet oils must have full capability in any proportion with any other similarly certified oil. The US Military also requires that qualified oils be compatible with other oils that meet the same specification.
Gas turbine oil coloring is determined by the additive package selected and can vary between oils. It is not an indicator of oil quality or suitability.
A certificate of compliance is a document similar to what's commonly referred to as a Certificate of Analysis (COA). COAs are filed for every batch of Mobil Jet oil produced. A COA can be obtained by contacting your ExxonMobil source point or downloading a copy from our website.
With regard to handling, please refer to the Material Safety Data Sheet (MSDS). Generally no special precautions are necessary beyond standard good hygiene practices. In addition, there is no need to shake, stir or otherwise agitate the oil before use. The ester base oils used in Mobil Jet™ Oil II and Mobil Jet™ Oil 254 gas turbine lubricants have excellent additive compatibility and long-term storage stability characteristics.
The shelf life for all Mobil Jet oils in metal quarts is 10 years, and five years for all products in pails or drums. We recommend effective inventory management be employed to ensure the stock of Mobil Jet oils is rotated for storage and use.
Many airlines prefer quart cans. Quart cans provide for ease in handling when performing reservoir "top-offs" during maintenance checks. Additionally, quart cans have a longer shelf life as a result of hermetic sealing. Jet oils are extremely hygroscopic due to their chemical composition; they can attract/pick up moisture from the air easily, even past the bungholes on pails and drums, due to expansion and contraction associated with temperature swings. Once a quart can is opened it is difficult to reseal, and as such, should be used entirely or disposed of. Reusing open quart cans increases risk associated with collection of moisture and/or other potential contaminants (e.g., dust, dirt, etc.), therefore it is recommended for single use application only.
Mobil Jet oils have a safe history of use in both ground and air operations for more than 50 years. ExxonMobil is not aware of any adverse long-term health effects associated with aircraft use of jet engine oils. Refer to the MSDS (Material Safety Data Sheets) for additional handling and safety information.
Hydraulic systems use a confined fluid to transmit power. The fluid used to transmit power is called a hydraulic fluid, or oil, and also functions to cool and lubricate the hydraulic system. Aviation hydraulic systems fulfill various functions, including moving flight control surfaces that help steer, take off and land aircraft. Hydraulic fluids help to engage aircraft brakes and deploy or retract landing gear.
Mobil HyJet products are fully compatible in any proportion with each other and with other commercially available phosphate ester based hydraulic fluids. Additionally, aircraft OEM require a multitude of compatibility tests, including compatibility tests with metals, elastomers, solvents and paints. Please contact your ExxonMobil aviation representative for specific compatibility inquiries.
Proper handling of Mobil HyJet products is well documented in the MSDSar.
Fire-resistant hydraulic oils are dyed purple to differentiate them from 5606 fluids, which are red in color.
Mobil HyJet IV-Aplus and Mobil HyJet V are fire-resistant hydraulic oils while other 5606 fluids are not considered fire-resistant. Fire-resistant fluids have evolved over time as commercial jet travel has become more prevalent. Fire-resistant fluids were developed to accommodate increased aircraft speeds during landing and withstand higher braking temperatures. Fire resistance properties of these oils include high auto-ignition temperature and zero flame propagation. Additionally, the oils must meet special OEM test requirements such as hot manifold ignition and high- and low-pressure spray tests, among others.
Conversion is typically completed using the “top-off” method in which Mobil HyJet products are added to hydraulic reservoirs as required to maintain proper fluid levels. Using this method, the original fluid will gradually be phased out as more “top-offs” occur. Please contact your ExxonMobil aviation representative for specific conversion suggestions.
Yes, ExxonMobil aviation offers Exxcare as a routine in-service fluid analysis program for Mobil HyJet customers.
Mobil HyJet V hydraulic fluid offers extended fluid life over Mobil HyJet IV-Aplus without sacrificing fluid performance in preventing wear, rust and deposits or increasing weight. Mobil HyJet V hydraulic fluid is also certified for use in 5,000 psi hydraulic systems.
The Mobil™ brand carries significant brand equity and is widely acknowledged as a premiere brand and leading supplier of high-performance lubricants. With the rebrand, our former Exxon products now align with and leverage the strength of the Mobil brand.
We recommend that exposure to high water concentrations, including precipitation and de-icing fluids on the tarmac, be avoided. Potential issues could involve hardening or softening of the greases, increased corrosion or decreased effectiveness of the performance additives. For greases formulated with ester base stocks, you may see increased hydrolysis or breakdown of the grease. To be safe, we recommend that technicians should evaluate their grease every 10,000 hours for irregularities and consult their supplier with any questions. Hydrolysis is preventable.
The use of contaminated greases can cause a wide range of issues, including deposit formation, reduced wear protection, increased wear, increased corrosion and reduced bearing life. We recommend that if a contaminated grease is used, the grease must be replaced immediately and the part should be examined for potential damage.
Base oils can consist of a wide range of fluids from low-viscosity mineral oils to heavy cylinder stocks to specialized synthetic lubricants. The inherent features seen in a base oil may also be seen in the grease, such as good high-temperature performance, oxidation resistance or low-temperature performance. Base oil selection is generally determined on the desired performance features of the grease.
While many base oils and additives used in greases have a defined odor when fresh, odors can also be the result of in-service degraded grease. However, ExxonMobil aviation greases formulated from 100 percent polyalphaolefin (PAO) base oil, such as Mobilgrease™ 33, will minimize these objectionable odors. Greases containing an ester base stock may be susceptible to hydrolysis and could generate an odor.
You can help minimize oil separation by storing oils in a climate-controlled environment and releasing pressure on the pumping devices used to apply the grease when not in use.
Flash point is the lowest temperature at which a grease gives off sufficient vapors that will ignite in air when exposed to an ignition source. The flash point of a grease is often governed by the flash point of the oil used in the grease.
Over-greasing of a bearing or component can lead to a number of issues, including high operating temperatures, seal failures and bearing failures.
The most common visual indicators to help you determine if a grease needs to be replaced are to look for any hardening, softening or significant color changes. More advanced techniques involve vibration analysis, used grease analysis or thermal imaging. A detailed lubes program analysis by your supplier will help you identify the key features you need to assess grease life in service.
A number of options exist for removing grease from your application or bearing. These can range from purging and wiping down the part to solvent washing of the part. It is generally recommended that you contact your OEM supplier to determine what is an acceptable method to clean the application or bearing.