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Do magnetic oil drain plugs really work?

If they do, they must be very strong magnets - wouldn’t they then magnetize the oil pan? If the oil pan was magnetized, then a magnetic sludge would form on the bottom of the pan and never drain out, right?

My oil-enthusiast mind needs to know!


When you ask “do they work”? What do you mean by that?

Will they attract and trap metal particles? Sure.

But the real question is:
Will they do anything that allows the oil and filter change interval to be extended?


Sorry I wasn’t very clear on my question…I meant are they strong enough to attract metal particles and keep them trapped until the next oil change?

Also, are there any possible adverse effects…such as a clump of ferrous shavings falling off the magnet when you hit a big bump and that clump then running through your engine, or the oil pan being magnetized?

Too bad they won’t extend the oil change interval (OCI).

They will hold small particles of steel, but not aluminum. The oil filter is effective at keeping these small particles from circulating through your engine, so a magnetic drain plug is not necessary. If they were useful all new cars would have them installed at the factory.

If you want to know more about oil, check out

Bob IS the oil guy.

Yes. The oil flow in the pan is not fast enough to sweep the particles off the magnet. The particles must get close enough to the plug to be attracted to it, but all that swirling while driving and pumping will mix the oil quite well.

They work great, especially in gearboxes. The magnets are powerful and effective.

They work, but with proper filters they really are not needed in modern engines.

Magnetic drain plugs are near worthless IMHO. They’re not going to attract any crankshaft bearing or cam bushing overlayment as that is non-ferrous material.

If you have enough ferrous particles stuck to a magnetic engine drain plug to worry about then metallic attraction is the least of your worries as this means the rings/cylinder walls are gone and you should have been burning oil.

If a transmission, automatic or manual, has enough ferrous particles to worry about then the transmission is on the way out anyway. Don’t go far from home.

Many gearboxes come with magnetic plugs or a simple magnet inside the pan (automatics). When serviced, these magnets are usually covered with fine black grit, metallic particles. They must be doing something…