The fine, furry layer of ferrous wear particles that builds up on magnetic drain plugs and chip detectors. A light coat of fuzz is normal, especially after break-in, while flakes, slivers or chunks point to pitting, spalling or a breaking tooth or bearing. Mechanics read the plug at every oil change as a cheap condition check.
Just fuzz on the plug, no chunks, so the gears are wearing normally, wipe it and button it up.
A gray paste is normal; flakes that glint like glitter or slivers you can pick up with your fingers are not.
Also heard as
- drain plug fuzz
- magnet fuzz
- paste
Related terms
Pumpkin
Shop name for the round differential housing in the middle of a drive axle, from its bulging shape.
Spalling
Large, irregular flakes broken out of a tooth surface, usually where pits have grown and joined.
Run-in
Operating new gears at reduced load at first so surface high spots wear smooth before full duty.
Grenade
Shop slang for a gearbox or axle destroying itself all at once, scattering broken teeth and bearing parts.