Food for thought: categories of lubricant contamination (aka, what we subject our oils to)

There are many obvious types of oil contamination, and some not so obvious. Which ones impact on your systems?:

Solid (dust ingress, generated wear debris etc)

Liquid (water, solvents, wrong oil etc)

Gas (air/oxygen)

Micro-organisms (bacteria, fungi)

Electrical (electrostatic discharge, stray current)

Heat (external or internal)

Radiation

Chemical

Magnetic

Can you add to the list?