"Fuel polishing??? Whoever coined that stupid, inaccurate phrase?"

The entire filtration industry adopted the term 'polishing' in about
1925. 'Polishing' via a filter means that the filter removes at a
maximum 0.05% (by weight) of debris per 99,05% (by weight) of liquid
filtered. So, 'polishing' can be be by recirculation or single pass
if the removal % is lower than 0,0005. Filtration removals at greater
than that .0005 level are called 'depth' or 'cake' filtration - this
has been the 'jargon of the filter industry for almost 100 years.