What does oil degradation refer to?

Oil degradation refers to the loss of effectiveness of the lubricant due to breakdown or contamination. Over time and under operational stresses, lubricating oil can undergo various changes that make it less effective in performing its primary functions, such as reducing friction, protecting against wear, and resisting oxidation.

During oil degradation, several processes can occur, including thermal oxidation, the formation of harmful byproducts, and the accumulation of contaminants such as dirt, water, or metal particles from friction and wear. These changes can lead to reduced lubrication performance, increased engine wear, and potential failure of machinery components if not monitored and managed properly.

The other options do not accurately capture the essence of oil degradation. For instance, an increase in viscosity or the stabilization of lubricant composition typically indicates that the oil is maintaining its properties instead of breaking down. Furthermore, enhancement of lubricant properties contradicts the definition of degradation, as it implies an improvement rather than a decline in effectiveness.