What is the term for an oil's ability to hold together under pressure?

The term that refers to an oil's ability to hold together under pressure is film strength. Film strength is critical in lubrication as it indicates how well the oil can maintain a protective film between surfaces under load. This property is essential for preventing metal-to-metal contact, which can lead to wear or failure of machinery. A higher film strength implies that the oil can withstand greater pressure without breaking down, ensuring effective lubrication during high-stress conditions.

Fluidity relates to the ease with which a fluid can flow but does not specifically address the oil's structural integrity under pressure. Density measures mass per unit volume and does not correlate directly to the oil's performance under load. Viscosity indicates a fluid's resistance to flow, but it does not measure the oil's cohesiveness under pressure like film strength does. Therefore, the understanding of film strength is vital in determining the suitability of an oil for specific applications where high pressure is expected.