I own two filter mags one for my oil filter and tranny spin on filter. Do they actually do anything, a buddy of mine owns a speed shop and says how great they are. Never got around to tearing a used oil filter open so i dont really know. ALso, I lost my magnetic drain bolt when i switched to the FRAM sure drain.

I have seen the imprint of the filtermag on the inside of my OEM fuel filter. It is catching particles. The real question is would the OEM catch the particles also?

I do not have one on the Allison, but I am thinking about it after I upgrade my Allison with Mike L.

Everytime I change the small allison spin on filter (I do several a week), I always clean off a noticeable amount of black material that has stuck to the mag. To me I would say it's doing it's job. Having one on the oil filter sure would not hurt.

One time I pulled a 1/4 x 3" carrige bolt out of the drain pan on an old CAT, it was stuck to the magnetic drain plug!

Are you in need of a drain plug? Before I replaced the OEM plug, I'd install a Famoto, or a magnetic plug.
I have a Filtermag on the OEM Fuel filter. I probably should put one on the tranny filter.

I've seen a real life example on a used fuel filter. It did leave a residue imprint on the filter canister. Like Ron said, would the filter catch it? Not sure. It is one of those, 'it can't hurt' and the prices are more reasonable than they used to be.

will i see any significant benefits from the Filtermag?