Other way around. Would heating otherwise usable materials, paraffin oils, remove any remaining napthenics and aromatics. I've gotten some really crap industrial mineral oil over the years. Definitely not FDA approved.
Naphthenes are lighter than Paraffinics, they have already been heavily separated from the longer chain paraffins with
catalytic reactions in the vacuum tower distillation fraction from which they originate and their corresponding physical-chemical properties are determined solely by the carbon chains that are present. Oils begin about C15 and run through C20, anything above that is the beginning of tar.
The naphthenics used for the ultra-refined lubricating oils were split out with hydrocracking. Hydrotreated, light naphthenic and heavy naphthenic oils have been partially or totally separated from paraffinic and mineral oils by that point. All of those start as Distillate Base Oils, to be called naphthenes or a naphthenic oil they must be at least 60% naphthenes and 30% paraffins in the worst case. The higher the naphthene ratio the higher the quality and the worse it is for BP.
You can’t just continue to “refine” naphtenic to get “more” paraffinics. The waxes are long gone, by definition there are no waxes in naphthenic oils. In short the paraffinics have already been largely removed. The residual paraffinics are such a small percentage of the remaining oil that you would end up with more of the carbon chains bordering on the C21 groups if you used heat to further drive off the lighter chains. It’s as I said you would have a tar like substance. Note even before I didn’t call it tar, because most of that was removed in the first cracking tower.
Refining naphthenic oils to try to increase the ratio of paraffinics would be akin to “distilling” a spirit like a barrel aged whisky to try and get water. You would drive off the alcohol, but the remaining “water” is not pure by any stretch of the imagination. It has the secretions and elements of the barrels it was stored in for years. It would be brown and not very tasty or a “pure water”. That would be analogous to your remaining oil, dark with poor properties and not very conducive to good BP usage. The only way to get pure water from the barrel aged whisky would be to drive off all alcohol first then to distill the water, then all impurities would remain in the distillation chamber, but you can imagine how little water you would end up with.
No one would you start with a highly refined naphthenic oil to get a paraffinic residue. It would be like someone buying expensive aged whisky to liberate the water for drinking. If you want water, then start with water, get purified water if you want a better water. If you decided to make all of your own distilled water or even purified water the start-up costs are high. If you want paraffinic oil or paraffinic products then start with those. Refined white mineral oil is an example of a refined paraffinic with all of the naphthenics removed.
I know you are asking about heating baseline paraffinics to "refine them", but cracking hydrocarbons is not as simple as just heating once you get to the longer chains. With the short chains like methane, etc. it actually is. You really aren't going to help yourself with simple heating, just like driving the alcohol off of the whisky won't give you pure water, you have to then distill the water. In a sense the same would be true with the oil. Oils and grease compatible with BP are relatively cheap, just buy those.
Even the less refined mineral oil you spoke of is probably just fine for BP, it doesn't have to be medicinal grade. Your body doesn't "digest" any of them, they all pass. The better ones just have lower residuals like the nahpthenics. I'll bet at some percentage it doesn't matter to BP residue anymore. Just like the Naphthenics have to be at least 60/30 the Paraffinics have to meet that same threshold, but inverted to be called paraffinics. But, as you know with the mineral oil there are many grades, I just can't say at what point they become "bad," but I'll bet you have a lot more leeway than you would with it being medicinally acceptable or edible.
Regards,
Mako