Don't use oil, don't use coatings.Oil disperses and evaporates too quickly, coatings will wear off rather quickly unless you have a means of pulling down a vacuum of a few atmospheres and opening the structure of the steel so the coating can penetrate.
I have been using grease on the rails of my 1911s for over 20 years. I've yet to have a problem with dust or dirt collecting in the grease and my guns have operated in some dusty, nasty places.
Basically, you guys are way overthinking this what with all these Space-Age lubes that allegedly work on the surface of the sun and spending way too much money.
I use Plastilube. Yes, it was developed during WWII. Yes, it isn't mucho-Tech sexy...it just works. I will direct you gents to the fact that Plastilube was/is the only lubricant specifically-developed for use in Semi-Auto and full-Auto weapons in a harsh environment. AAMOF, much harsher than any of us will ever see. A very small dab on each frame-rail, front, middle and rear, is all you need. I've fired up to 500 rounds of full-power 45ACP through 1911s lubed like this and at the end, the lube was still there and working.
Just a thought, jjjuuusssttt a thought.