They are nice, but bulky, messy to clean and require a gravity drain.

The Amsoil bypass filters work nearly as well and you can plumb the return oil to any convenient location (such as providing extra lube to the timing chain).

I use several neodymium magnets from hard drives in several places. 5 on my bypass oil filter and one on my lower oil pan by the drain.

Lets look at the cost effectiveness there.

Centrifugal filter
Initial cost: $350
Yearly cost: $0

Amsoil bypass filter
Initial cost: $25 filter base, $35 filter= $60.
Yearly: $35

Time until the centrifugal filter has paid for itself: 9 years.

I thought they were around $250 (used ones also show up on Ebay once in awhile for less ).
At the end of the 9 years if it is still working you can use it on another Vehicle or you could sell it and recover some of the initial cost.

It might be interesting to hook up a Amsoil Filter and run the Oil that has past through the Amsoil Oil Filter through the Centrifugal Filter and see what actually gets past the Amsoil Filter.

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84 300D, 82 Volvo 244Gl Diesel