Now this is a mild benefit that others might not care about, but the magnet allows you to see the effects of changing brands of oil by changing the amount/size of the particulates captured.

I noted a decrease in number/amount and a finer size of trash after changing from Mobile 1 to Rotella T-6 which was information of a sort although nothing "definitive".

http://www.supermagnetman.net/product_info.php?cPath=41&products_id=404



People keep harping on the cost -- mebbe some places charge a lot of money for a supermagnet but this magnet right up above costs less than $10 and you don't have to do anything but pop it on the outside surface of your oil can -- the spring goes through the center with lots of clearance and it doesn't weigh enough to do anything to your filter mounting system when you go over the bumps.

BTW, that fuzzy picture is the entire oil filter and magnet hanging from the corner touch of a paperclip to the same side of the filter can -- supermagnets got that name for a reason !!!

Protection goes up and you have the chance to have a cheapie Emgo oil filter act like an expensive fine filtration unit for periods of over a year (multiple oil changes for Dino oil, or if you run a synthetic oil like T-6 you can run a once a year change cycle with a 2 year filter change).   I am not saying you should do this (silicates do build up over time) but you can do it as I have done it just to see what builds up in the filter pleats.  

The enjoyment you get from playing with your ring magnet makes filter change time almost fun instead of the messy expensive drudgery it winds up being otherwise.

"What did my ring magnet catch this time?"    

"Does my new oil work any better?"    



            Weeeeee !!!



Example

I changed back to dino oil for one oil change at the recommendation of the Web Cam people when I first put my high stepping stage 2 cam in place.  The size and amount of trash I found at the next short interval oil change was right back at the levels I had seen before going to T-6, so I quickly went back to T-6 for my running oil and the trash level went back down again.