Magents for engine drain plug, transmission pan and differential drain plug?
 

I've seen various vendors offering magnetic drain plugs for the oil pan, differential and transmission pan. The claim is they keep metal debris from circulating. It seems like a good idea but what say you?

I'd say sure. I don't think they will hurt anything, but hopefully your engine and trans aren't shredding themselves to begin with.

On our Honda Odyssey this is a different story. The trans is undersized, doesn't have a cooler and I regularly clean the magnetic drain plug of clutch material.

It is definitely a good idea for the differential since it has no protection whatsoever. THe engine and transmission have filters. However I put magnets on everything recently, I'll have to report on how it works out after a few months of observation.

Magnetic Plugs, Drain/Fill
 

SWARF is always present in any machinery so the addition of magnets anywhere in the lubricants is wise .

Many older machines & vehicles came with sump oi magnets before WWII .

For ****s & giggles I began adding them to the fill plugs too and was surprised to see finer SWARF collect on the fill plugs and larger, more jagged SWARF collecting on the drain plugs .

Harbor Freight sells nifty little tubes of rare earth magnets that are disc shaped, they're dead simple to add to the nose of any drain plug .

Just remember to occasionally CHANGE THE OIL and clean the magnet .

I think the only drawback could be if the magnet being used can't handle the heat and becomes weak or even demagnetized.
https://www.first4magnets.com/tech-centre-i61/information-and-articles-i70/neodymium-magnet-information-i82/how-does-temperature-affect-neodymium-magnets-i91

Heat & Magnets
 

That has never, ever occurred .

I run magnets in air cooled engines that exceed 250* F oil heat and never had one yet .

Don't look for things to be afraid of .