Vintage BMW Motorcycle Owners

Jim,
You asked me:
What would be the best way to attach the magnets if an aluminum oil pan is used?

Instead of putting the magnet directly in the oil pan, put it on top of the steel, screened oil pickup. Then, when you do drop the pan to clean the "hair" off the magnet, you will have to remove the pick up screen, remove the magnet, and clean the filings that are stuck in the inside of the pickup with spray carb cleaner and compressed air.

Vech
My sidecar bike has the aluminum pan. The other 2 solo machines have the steel pan. Thanks for your response to my question. I will order magnets for them.
Jim

Echoing Vech,
I have used https://www.millennium-tech.net/
They were very communicative, timely and reasonably priced.
I had them bore and silicon coat my cylinders. They paint the outsides very nicely as well. I don't know if they are powdercoated.
On a cynical note, I have to take their word they did anything...I can't see any difference. I guess I'll know in 150,000 miles.