^ agreed,
You'll see a paste of metal particles slabed on the magnet.
You can buy some cheap neodymium magnets on ebay and stick it on the oil filter, drain plug, tranny plug, and diff plug, and you'll see it.

Underdrive pulley, Low temp fan switch, greddy oil pan are what I'm looking at(because its do-able at home).
Rotary engines' weakness is heat, so any mods that cools the water and oil down efficiently leads to longevity, I guess..