I just put a magnet on the oil filter

 

Great idea! Have you ever cut open a filter to see what got caught by the magnet?

 

Dimple is the brand I have on my bike now. Purchased a decade ago. No longer in business. Vortex is another US brand I've heard of.

I've messed around for many years with magnets on oil filters, with and without magnetic drain plugs.
Nothing ever in the filter next to the magnet (multiple locations on filters, multiple bikes). The magnetic drain plugs always have something on them.

The one location I've found that a magnet works is on my air compressor. I placed the magnet on the oil drain tube just outside of the crank case. It does not have an oil filter.

 

The one location I've found that a magnet works is on my air compressor. I placed the magnet on the oil drain tube just outside of the crank case. It does not have an oil filter.

I've never considered that. Just assumed that there was no wear.