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 This hydraulic fluid is blended with highly refined mineral based oils and modern additive technology to provide protection against rust, wear, demulsibility, and to afford greatly improved viscosity - temperature characteristics as well as enhanced oxidation – corrosion resistance.

This specification covers a class of fluid for use in the hydraulic transmission of power.

MIL-DTL-17111C Intended Use
The fluid covered by this specification is a medium to be used in connection with hydraulic transmission power.

MIL-DTL-17111C Subject term listing
Subject terms listings are Hydraulic mineral oil, petroleum, and icresyl phosphate.

MIL-DTL-17111C Materials
The fluid shall consist of mineral oil products plus 1.0 ± 0.1 weight percent of tricresyl phosphate conforming to TT-T-656 and approved additive materials for improving the finished product with respect to the viscosity-temperature and lubricating characteristics, resistance to oxidation, and protection of metal parts against corrosion.

MIL-DTL-17111C Suitability
The fluid shall be suitable for use in hydraulic systems involving mechanical or fibrous type filters or centrifugal purification. It shall be noncorrosive to bearings and hydraulic systems and shall not cause clogging of oil screens or valves. The fluid shall remain homogeneous over the temperature range of -34 °C to 4 °C.

MIL-DTL-17111C Low temperature turbidity
A dry sample of the fluid shall be stored at a temperature of 37 °C for not less than 72 hours. After that time at the storage temperature, the fluid shall show no evidence of gelling, crystallization, or separation, and shall develop a turbidity not greater than that exhibited by a standard suspension of barium sulfate in water.

MIL-DTL-17111C Rust prevention
The transmission fluid shall prevent the formation of rust.

MIL-DTL-17111C Corrosion and oxidation stability
The finished fluid must encompass both resistance to oxidation and protection of metal parts against corrosion.

MIL-DTL-17111C Packaging
When packaging of materiel is to be performed by DoD or in-house contractor personnel, these personnel need to contact the responsible packaging activity to ascertain packaging requirements. Packaging requirements are maintained by the inventory control point’s packaging activities within the military service or defense agency or within the military service’s system command. Packaging data retrieval is available from the managing military department’s or defense agency’s automated packaging files, CD-ROM products, or by contacting the responsible packaging activity.



MIL-SPEC, military specification, military standard (MIL-STD) is a United States Defense standard used to describe a product that meets specific performance and manufacturing standards for equipment and chemicals.

Other non-defense government organizations, technical organizations and industry may also use military specifications are not just limited to The Department of Defense, as other government organizations and Industry use them as well.

Here is a Q&A from the Department of Defense:

What is a performance spec?
A. A performance specification states requirements in terms of the required results with criteria for verifying compliance, but without stating the methods for achieving the required results. A performance specification defines the functional requirements for the item, the environment in which it must operate, and interface and interchangeability characteristics.

Q. What guidance have we given on how to write a performance specification?
A. Writing performance specifications is not a new concept. We have been teaching how to write performance requirements for years at our specification training course. It has received extra emphasis in our training on how to write Commercial Item Descriptions. What is new is that we are now designating documents as "performance specifications."

Q. If you have a performance spec that is MILSPEC, is a waiver needed?
A. No.

Q. Is it possible for a general specification to be designated as performance and its associated specification sheets to be designated as detail?
A. No. Since a general specification must be used together with a specification sheet, the fact that the specification sheet is detail requires the general specification also to be designated as detail.

Q. Within the same family of specification sheets, is it possible for some to be designated as detail and others to be performance?
A. Generally, no. The decision whether to convert a family of specification sheets to performance specifications must be consistent across-the-board. In some cases, however, the number of specification sheets that must be converted to performance specifications may be very large, making it difficult to convert all of them at one time. In this situation, there may be a temporary blend of detail and performance specification sheets within the same document number series. This situation is acceptable as long as the goal is to convert all of them to performance specifications.

Q. Can a performance spec ever cite a detail spec as a requirement?
A. The citing of a detail spec as a requirement does not automatically mean that a spec is not performance, but it is a strong indicator that as spec may not be performance. Performance specs should not cite any detail spec as a requirement if it demands a specific design solution. But performance specs may cite a detail spec if it relates to a physical or operational interface requirement.
For example, it would be permissible to have a requirement in a performance engine specification that required the engine to operate with specific substances, such as lubricating oil or fuel, which conform to detail specs. The requirement that the engine be able to operate on a specific type of fuel is an operational interface requirement and does not dictate the specific design of the engine. However, it would not be permissible in a performance spec to require the engine be made of certain materials or that the various engine components conform to detail specs since such requirements would dictate specific design solutions instead of stating the performance expected.

Q. I'm writing a spec that describes a "kit."
Should it be a detail (MIL-DTL-) or a performance (MIL-PRF-) specification?
A. In general, the answer is that it will likely be a detail specification; however, there can be exceptions. A spec for a kit describes a collection of related items, such as adapters, couplings, bags, tools, attachments, or accessories. A kit may contain items for installing, testing, or starting up a system or piece of equipment; it may be provided to equip an existing system for specific functions; or it may be used to adapt equipment to meet new or specialized conditions. If the spec writer were careful to write all of the requirements for the kit's contents in terms of form, fit, function, and interfaces, and to cite only performance-type documents, the resulting spec would support a MIL-PRF designation. As is frequently the case, however, if one or more of the kit's components are described using a specific design solution, Technical Data Package, MIL-DTL type spec, or a non-government standard that contains detail design requirements, the kit spec must be designated as a MIL-DTL. The spec writer needs to keep in mind that all of the requirements for all of the kits' components must be stated in performance terms in order to produce a MIL-PRF.