MIL-PRF-23699: A Common Military Aircraft Turbine Engine Oil

If the military aviation fleet rides on the backs of lubricants and oils (it does), then the main event is MIL-PRF-23699, which is basically the benchmark turbine engine oil common to dozens of engines and used on many airframes in the fleet. 

It is also one of the most heavily procured turbine oils in the world, both militarily and civilian due to its wide use, and it is sold by several major oil & lubricant makers under different brand names. Let’s take a look at one of the most common aircraft gas turbine jet oil types in production. 

MIL-PRF-23699 Specification

MIL-PRF-23699 is the military standard performance jet oil that is used in a ton of different engines. One of the most prolific users is the entire KC-135R fleet which uses it, but it is also used in the F-15, F-16, and F-35 to name a few. 

It is also used in some gas turbine engines as the primary oil for marine-use engines, which are common in some ships, boats, etc. 

  • MIL-PRF-23699 is a U.S. Military Specification for turbine engine lubricating oil.
  • The specification outlines the performance requirements for gas turbine engines used in commercial and military aircraft.
  • It covers the physical and chemical properties of the lubricating oil, including thermal stability, oxidation stability, and corrosion resistance.
  • The specification also includes requirements for the lubricating oil’s compatibility with various materials used in gas turbine construction.
  • It is a widely recognized standard for turbine engine lubricating oil in the aviation industry.

MIL-PRF-23699 is a military spec for synthetic lubricating oils used in aircraft turbine engines. Here are the details:

General Description

MIL-PRF-23699 is for synthetic base lubricating oils for gas turbine engines. These oils are formulated for high thermal and oxidative stability, corrosion inhibition and compatibility with various engine components. Replaces MIL-L-23699 and has three classifications: Standard (STD), Corrosion Inhibiting (C/I) and High Thermal Stability (HTS).

Key Characteristics

  1. Viscosity
  2. Thermal Stability
    • -40°C to 204°C (-40°F to 400°F) operating temperature range.
    • For hot running engines to prevent oil coking and degradation.
  3. Corrosion Resistance
    • C/I class oils for corrosion protection especially in moist environments or during extended periods of inactivity.
  4. Compatibility
    • Compatible across all classifications (STD, C/I, HTS) but mixing reduces specialized benefits.
    • Elastomer compatibility testing for minimal swelling and degradation in seals.
  5. Environmental Impact
    • Biodegradable formulations available for certain classifications.

Properties and Performance

All oils are not the same. Turbine engine oils have to operate in extreme altitudes, temperatures, and conditions all while lubricating components that are operating at many thousands of RPMs. Aircraft gas turbine engines routinely operate up to FL450 and can turn up to 14,000 RPM depending on the engine stage and operation. 

Because of these routinely extreme conditions, MIL-PRF-23699 and its derivatives are made to withstand extreme temps and provide high thermal stability to resist deterioration and deposit formation.

It also has excellent oxidation stability to maintain the physical characteristics required by builder and military specifications (which are often for the same engines like the CFM56 and PT6 series engines that power dozens of different aircraft. It provides good load-carrying capacity and corrosion resistance to minimize engine wear.

One of the most impressive features is its ability to provide low temperature fluidity to ensure reliable lubrication in low temperatures. 

Brands Offering MIL-PRF-23699 Equivalent Oils

Several brands manufacture oils that meet the MIL-PRF-23699 specification, ensuring high performance and reliability for turbine engines in both commercial and military service.

  • Mobil Jet Oil: Known for its high thermal stability and excellent oxidation stability, Mobil Jet Oil is a popular choice for aircraft engines. It is engineered to provide optimal performance under severe operating conditions.
  • ExxonMobil: This brand offers a range of turbine oils designed to meet the demanding requirements of gas turbine engines, ensuring reliable operation and reduced friction.
  • Shell AeroShell Turbine Oil: Shell provides a variety of turbine oils that meet the MIL-PRF-23699 specification, known for their excellent thermal and oxidation stability, making them suitable for high altitudes and low temperatures.
  • BP Turbo Oils: BP offers turbo oils that are formulated to meet industry standards and military specifications, providing excellent corrosion resistance and deposit control.
  • Castrol: Known for their innovative formulations, Castrol's turbine oils meet the MIL-PRF-23699 standard, ensuring high performance and reliability for both industrial and marine applications.

These brands ensure that their turbine oils meet the rigorous testing and performance capabilities required by the MIL-PRF-23699 specification, making them suitable for a wide range of applications in aircraft gas turbine engines.

Most of these alternatives, which are completely safe and authorized for military use in aircraft calling for MIL-PRF-23699, are available and easily sourced through GSA Advantage for government and military procurement. Here are some of the options available from Greenwood Aerospace:

→ Eastman Turbo Oil 2380 Clear MIL-PRF-23699 Spec Aircraft Turbine Engine Lubricating Oil - Quart Can

→ Eastman Turbo Oil 2197 Clear MIL-PRF-23699 HTS Spec Aircraft Turbine Engine Lubricating Oil - Quart Can

→ Royco 560 MIL-PRF-23699 HTS Advanced Synthetic Turbine Oil - Quart Can

Mobil Jet Oil: A Popular Choice for MIL-PRF-23699

Mobil Oil makes some of the most widely used and common petroleum products in the world and their turbine engine oil for turbo jet applications is no exception. Mobil Jet Oil is a synthetic lubricating oil formulated to meet the demanding requirements of latest technology aircraft-type gas turbines. It meets the highest demands of MIL-PRF-23699 oil specs and is an approved option for any engine using this oil. 

It is approved against the High Thermal Stability (HTS) classification of the U.S. Military Specification MIL-PRF-23699, meaning whatever the thermal demands of the MIL-PRF-23699 are approved for, this will also meet or exceed. 

Mobil Jet Oil is a third-generation, extra high performance, synthetic aircraft-type gas turbine lubricant engineered to meet the performance requirements for gas turbine engines, and it has a shelf life of 3,650 days.

Health and Safety Considerations for Turbine Oil

As with all oils, lubricants, and other petroleum items, there are considerable health and safety considerations for use with turbo oil. Here are some best practices:

  • Health and Safety recommendations for turbine oil can be found on the Material Safety Data Sheet (MSDS). These are required in all industrial areas in the proximity of the 
  • It is important to follow proper handling and storage procedures for the safe use of turbine oil.
  • Turbine oil should be disposed of in accordance with local regulations and guidelines. Never let it drain onto the ground. 
  • It is recommended to wear protective clothing and eyewear when handling turbine oil. You need oil-resistant or oil-proof gloves and eyewear at a minimum, and a rubber apron is always advisable. 
  • In case of an emergency, contact the manufacturer or a medical professional for assistance.

Final Thoughts on MIL-PRF-23699

Greenwood Aerospace is your #1 stop for MIL-PRF-23699 equivalent oils to run in your fleet. We sell them by the quart, and have several of the top brands available, so whether you are operating a single C-12 Huron for your state TRANSCOMM asset or a fleet of turbine aircraft, we’ve got you covered. 

Check out GSA Advantage for all of our listings, or you can also contact us directly at email (contact@governmentprocurement.com), phone (580) 762-2580.