It only needs to be done once if done properly. I don't trust some kid at the LBS making 8 bux/hr to properly protect my new frame with some expensive, watered-down linseed oil from a spray can, so I always do it myself. One of the two commercial "framesaver" aerosol products is linseed oil diluted with a solvent to make it less viscous, easier to spray and less likely to plug the nozzle. You can buy boiled linseed oil (the active rustproofing ingredient), more than you'll ever need, for 1/4-1/2 the cost of a can or two of framesaver, then DIY and likely get better results. I bought a quart of boiled linseed oil, a pistol oiler and appropriately sized clear tubing from the hardware store years ago. This is all you need to completely rustproof about a half a dozen steel framesets.

Rustproof the frameset right after you get it home, before bolting anything on, while you're waiting for parts deliveries. It takes 5-7 days for linseed oil to dry to a hard tacky film, and ideally you need a garage or shed for the drying to occur, so you don't have to smell linseed oil inside your home. Do one tube at a time (down, top, seat etc). Take your time sloshing the oil around inside the tube to ensure coverage of all unfinished steel surfaces. Dispose of rags/paper towels/cardboard you use in the rustproofing process, as they apparently have some potential to start a fire.

Rustproofing is unnecessary if you live and do all your tours in dry, arid areas (CA/AZ/UT etc). If you live/ride where there is regularly high humidity or near a sea coast, then rustproofing is a good idea to ensure long life of a steel frameset.

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