Final answer:
Mineral spirits solvent is preferred for degreasing the disassembled parts of an engine during overhaul because it is more effective at dissolving oil-based residues, doesn't leave moisture that could cause corrosion, and evaporates quickly.
Step-by-step explanation:
The correct answer is that during overhaul, the disassembled parts of an engine are usually degreased with some form of mineral spirits solvent rather than water-mixed degreasers primarily because mineral spirits are more effective in removing oil-based substances. Water-based cleaners can cause rust and corrosion on metal parts and are less effective in dissolving grease and oil.
Since engines operate at high temperatures and involve oil-based substances, it's important that all residual oils are completely removed from engine components during cleaning to ensure proper function. The use of mineral spirits as a degreaser ensures that the parts are thoroughly cleaned without leaving any moisture that could lead to corrosion or other issues. Mineral spirits evaporate quickly, which reduces the moisture exposure of the engine parts. This is essential in maintaining the integrity of the engine components and preparing them for reassembly and operation.