Lubrication engineering: mineral oils are preferred over fatty oils as lubricants primarily because fatty oils exhibit which disadvantages?

Introduction:
Choosing between mineral and fatty (vegetable/animal) oils depends on stability, cost, and performance under operating conditions. This question asks why mineral oils are generally preferred in industrial lubrication.

Given Data / Assumptions:

• Mineral oils are petroleum-derived hydrocarbons.
• Fatty oils are triglyceride-based and contain ester linkages.
• Industrial conditions may involve heat, oxygen, and moisture.

Concept / Approach:
Fatty oils contain ester bonds susceptible to hydrolysis in moist environments, producing acids that corrode metals. They also oxidize more readily, forming gums/varnish that impair machinery. At higher temperatures, triglycerides decompose more easily than refined mineral basestocks, increasing deposits and viscosity instability.

Step-by-Step Solution:
Assess thermal stability: fatty oils decompose sooner at high T.Assess oxidative stability: fatty oils oxidize faster → sludge/gum.Assess hydrolytic stability: ester linkages cleave in water → acids/soaps.Conclude that all listed disadvantages apply to fatty oils, hence mineral oils are preferred.

Verification / Alternative check:
Lubricant datasheets and ASTM tests (oxidation stability, hydrolytic stability) consistently show mineral oils and synthetic hydrocarbons outperforming many triglyceride oils under severe industrial conditions, though some specialty esters are engineered for stability.

Why Other Options Are Wrong:

• Any single disadvantage alone understates the broader set of issues; all three are relevant.

Common Pitfalls:
Confusing modern synthetic esters (engineered for stability) with natural fatty oils; the question pertains to traditional fatty oils (e.g., vegetable/animal fats).

Final Answer:
All of the above