When cleaning aluminum and magnesium engine parts, why is it inadvisable to soak them in soap solutions?

Soaking aluminum and magnesium engine parts in soap solutions is inadvisable primarily because some of the soap can become impregnated in the surface of these materials, which may lead to contamination. Aluminum and magnesium are both relatively soft metals that can absorb foreign substances when subjected to prolonged soaking. If soap residues are left on the surface, they can interfere with subsequent processes such as painting, anodizing, or sealing, ultimately affecting the performance and longevity of the components.

When cleaning such materials, it is crucial to use cleaning methods that effectively remove contaminants without leaving residues that can compromise the integrity of the metal. For this reason, industry practices typically favor alternatives that do not risk leaving soap or chemical residues behind, ensuring that the metal surfaces remain clean and ready for further processing.