Which characteristic of oil is crucial for maintaining lubrication under high temperatures?

The crucial characteristic of oil for maintaining lubrication under high temperatures is its resistance to breakdown. When oils are subjected to elevated temperatures, they are at risk of oxidative degradation and thermal breakdown, which can lead to the formation of harmful byproducts. If an oil cannot resist breakdown, it will lose its lubricating properties, increase friction, and possibly lead to engine wear or failure.

Resistant oils maintain their viscosity and chemical stability when exposed to heat, ensuring that they continue to provide effective lubrication. This characteristic is essential in preventing increased wear and tear of engine components, thereby extending the service life of machinery and engines operating under high-temperature conditions.

In contrast, low viscosity might imply that the oil flows easily but does not guarantee that it can withstand high temperatures without breaking down. Low acidity is relevant but not directly related to the high-temperature performance of lubrication. High filterability is important for ensuring clean oil circulation but does not directly address the oil's ability to perform under elevated temperatures.