Why is it inadvisable to soak aluminum and magnesium engine parts in solutions containing soap?

Soaking aluminum and magnesium engine parts in solutions that contain soap can indeed lead to contamination because some of the soap may become impregnated in the surface of the metal. This phenomenon occurs due to the porous nature of aluminum and magnesium alloys. The soap particles can infiltrate the microscopic spaces on the surface, making it difficult to remove completely even after rinsing. The presence of soap residues can lead to issues such as improper lubrication, reduced adhesion for subsequent coatings or finishes, and potential interaction with other chemicals that could compromise engine performance.

Understanding this property is crucial, as maintaining the integrity of the engine components is vital for their longevity and function. Regular cleaning methods that don't involve soaking these metals in soap solutions are recommended to avoid these complications.