What is a unique characteristic of oils formulated under specification 2190?

Oils formulated under specification 2190 are known for their superior water-separating capabilities, which is essential in many hydraulic and lubrication applications. This characteristic ensures that water, which can be detrimental to lubricant performance, is effectively separated from the oil. This separation is crucial in preventing emulsification, which can lead to decreased lubrication properties, increased wear, and potential system failures.

In contrast, while high corrosion resistance, low viscosity, and high flash point can be beneficial properties of lubricants in various applications, they are not the primary focus of specification 2190. The emphasis on water separation in this specification directly relates to enhancing the oil's performance in environments where moisture exposure is prevalent, thus making it the distinctive feature of oils that meet this specification.