I have been speculating on this for some time.
The original synthetic oil was developed by Al Amatuzio, and his company was AmsOil.
http://www.amsoil.com/ He had the patent on it but that patent ran out more than a decade ago, and that is when Mobil1 and all the other automotive oil brands of synthetic came out. All the modern automotive synthetics are Amatuzio's synthetic. That much I know for certain.
Now, I'm guessing on this next part, but I'm thinking that Militec (which I use) and all the others are all the same synthetic that Amatuzio developed. That oil was (and is still) available in different viscosities, from a range of engine oils, to heavier gear lube, to light weight oil similar to WD40 they called MP, or Metal Protector.
All the gun oils, available now since there is no patent restriction, I'm guessing again, are the same basic stock, with perhaps a little bit of additives, but I'm wondering if the basic oil isn't Amatuzio's synthetic. It would be interesting if someone was in the industry and really knew the story and could tell us.
Buy the way, I used AmsOil MP on 2 very old long guns that were starting to show a little rust on the outside of the barrels. Just a light wipe of MP on the outside of the barrel and they not only cleaned up nicely, but all rust has stopped and they look great.
And no, I'm not a dealer so that is not an add.
One more thing, if Militec is the synthetic that Amatuzio made, then heating it would only serve to get rid of additives, not the base synthetic, since the synthetic can take very high temps, and your polymer frame would not do well at those kind of temps. Furthermore, Amatuzio's synthetic was very good at penetrating not only the surfaces between metal parts, but actually gets into the pores of the metal, then stays there due to a small electromagnetic charge.