Peter shared his use of magnets on his oil pan. Tom/Ray (who I normally always agree with (LOL)) said this would do nothing for him and it is the oil filter’s job to remove particulates. BUT what they forgot was: A. The oil filter is after the oil pump. You save all kinds of trauma to your oil pump without these bitts. I have rebuild a lot of motors with deep grooves in the oil pump lobes/surfaces (usually after we drag raced and killed the motor). B. Think about how much you save your oil filter not to have these bitts stuck in it. As the effectiveness of the magnet on the outside. Remember the steel oil pan itself will become magnetized so the filed will go right through the pan (unless you have a carbon fiber pan… but then it would stick either…)
I have inspected many an Aicraft and auto engines and found that the pumps were grooved as you mentioned, but it was in many cases due to cavitation of the pumps. Either insufficient oil or oil leaks.
In some cases metal was found in the filters and this usually would mean that something was comming apart. If this metal was magnetic, is was not bearings but could be gears. If it was not magnetic, it was the bearings.
I can’t se the pupose of the magnets mainly because one can’t see in the crankcase. If there is a lot of metal that attaches to the magnets, I quess the engine won’t last much longer.
Many cars have magnetic drain plugs. Some don’t. There does not seem to be any difference between them. This seem to be one of those good ideas that in reality does very little.
I think that the magnetic drain plugs are a good idea. They come standard on the Chevy vans I work on, and Dorman sells them in other sizes in their catalog.
They figured out that most particles big enough to damage the oil pump won’t get past the pickup screen. Magnets don’t cost a lot and you can keep them forever, unless the guy at zippy lube steals it. If you like magnets, then you can’t live without one.