The coating on the motor can be baked on road sealant, or cosmoline usually applied to bare metal before shipping. Also, PEople use some stuff for detailing engine compartments to make them shiny, but it leaves an oil slick that when applied to high heat with some dirt and dust, bakes into a yellow to black laquer.
I wouldn't worry about the mileage too much on a well maintained bike. I know Most Ducati owners seem to think their bike will melt if applied to the road for too long. I recently picked up a 09 696 with 77k miles on it. It was used a a comuter for someone who probably didn't want to load up the miles on his porsche. Aside from a belt failure that stuck the valve back in the verticle head sideways, and alot of road grime and packing grease from chains, the bike was mechanicaly in great shape. I stripped the bike down completely and I'm rebuilding the engine now. The bearings, bushings, trans, cams, crank were in excelent condition. I had some abrasion on a harness at the head tube and some corrosion on the swingarm pivot. Small easily repairable stuff for so many miles aside from the belt failure.

after some reassembly with a $300 motor with 3k miles on it from ebay

And running

I'm actually going to post a gallery of the rebuild of the original engine later on.