Military aircraft engines and hydraulic systems depend on specialised synthetic oils and fluids that armed forces buy as consumables. These purchases go through supply contracts rather than through the platform programmes that dominate the debate on European rearmament. The consumables are nevertheless governed by a dense layer of technical rules. Under the United States military specifications that govern the synthetic turbine oils and hydraulic fluid at issue, an oil is not eligible because it has the right chemistry. It is eligible because a named product, made by a named manufacturer at a named plant, has passed qualification and remains on a list. Any change to the source of its base stocks or additives, or to the place where it is blended, is treated as an event that may require new testing. European buyers add their own layer: French defence procurement, for example, requires national homologation for many of the fluids it buys. Specialist manufacturers sit inside this system. One of them, the French group NYCO, operates the only European production site that appears in the four qualification records in which its products are listed. That raises a question that matters to planners, procurement officials and investors alike. How far does control of qualified formulations and named production sites give a specialist supplier a durable position in military lubricant supply in Europe, and how quickly could a buyer change product, ingredient source or plant without a new approval? The answer turns less on market share, which no public source discloses, than on four things: how qualification works, where the qualified plants are, who controls them and how purchasing authorities actually buy.