"Easiest way is to have item sand/media blasted and primer immediately.... The cost of media blast is way cheaper than you doing it your self when you apply a hourly rate to your time. yes you say your time is free, well it ain't true if you consider food, lodging, materials, and other work not getting done..."
About 12 years ago I bought a used blower.
Took it to a DIY sand blasting installation, did a complete blasting job, brought it home and immediately primed it with Tremclad primer.
Now 12 yrs later only the 'impacted parts', like fan and chute have lost paint. All the rest of that blower has retained the original finish.
I still, to this day, feel that the time invested back then was well worth it, helped in that the used buy was a good deal, especially since I got 12 years good service with many more to come since I recently changed all the bearings and did minor repairs.