Okay.
I think.... I think I agree with just about everything everyone has said here. MY results were inconsistent. But the idea of oil curing is to render a TOTALLY consistent finish product - all pipes tasting and behaving the same.
The idea is that you somehow replace some horrible tasting tannins/sap with something pleasant, or at least seal it away. I boiled a stummel in oil for about 6 hours once, and tasted the oil. It tasted like.... oil. No difference in color or taste that I could determine, so it wasn't leaching much out of the wood in that time. However, I buy blocks that are theoretically quite clean in this regard, having been boiled and dried once already.
The taste in smoking is noticeable, at least for awhile. I kind of think that oil cured pipes maybe absorb a little less, act a little less like a filter, than an air-cured pipe. But that's truly about it. I have a Dunnie, a Wiley, and a Radice, and the Radice for outright smoking might be the best of 'em. And I have pipes that I know were not oil cured that I think out perform these, with certain blends.
So I think at this stage of the game, it's a preference thing. Some guys work real hard at it and perfect a process that lends their pipes at the very least a slightly recognizeable flavor, if not outright gains in the smoking department. I wrecked some really nice stummels fooling around with it, and gave up. The identical process yielded one pipe that stunk, and another that was terrific.
Radice gave it up - obviously people weren't flocking to the brand because of it, and you'd think that if it was THAT much better, people would drop "ordinary" pipes and get oil cured ones.
I recently was looking at Ashtons and thinking "Huh, maybe I should grab one of these." and then I went and bought a Savinelli Autograph, cuz you give me that old Italian wood and I'll put it up against the oil-cure any day. If the Ashton were the shape of the Sav I bought..... I would have bought the Ashton.
I just bought a 60 dollar pipe out of greece, and it was made 30 years ago. There's nothing fancy about it, no magic at all. Just a stem and a bowl, and it smokes crazy, crazy good, because the briar was treated correctly after it was cut, and then it sat awhile.
So if it pleases you to purchase an oil cured pipe, or hunt down that unsmoked Dunhill from 1936.... God, go do it. This IS part of the fun! But don't be disappointed if it's just a pipe after all.