Mike Veach, in earlier posts on this forum, and Chuck Cowdery in his book, have commented that bourbon from decades past stretching to pre-Prohibition times tasted and looked (in the glass) noticeably oilier than bourbon today. Amongst the congeners of non-rectified alcohol are various oils (fusel oils so-called) that probably accounted for that taste and texture. It is a goal of modern distillation largely to eliminate these from spirits, however. When thinking of this I was also pondering the fact that some Irish whiskey is noticeably oily in taste and texture: the potstill Redbreast comes to mind in particular. I note that such oiliness in Irish whiskey makes the drink fuller, softer, easier to swallow. Contrarily much modern bourbon is not oily. Its texture often depends on wood sweetness (good as far as it goes) but sometimes even quality whiskey feels a bit rough, too "clean" in this respect. I am wondering if modern bourbon distilling, albeit that it meets the legal standards for bourbon, may be rubbing out the oily quality of whiskey. The 1800's whiskey blending manuals warned (for health reasons) against adding glycerine to neutral spirits to imitate whiskey. The injunction shows however that a smooth, slippery texture was considered part of old time whiskey taste, as Messrs. Veach and Cowdery seem to have confirmed by sampling whiskies bottled many a year ago.
I decided to add a few drops of Mazola corn oil to a glass of bourbon - what better oil to add than one from corn? Modern oils are refined to make them mild in taste, but Mazola tastes to a degree of corn and offers certainly the texture of a true oil. It is remarkable how this improved the bourbon. I added literally only a few drops to two fingers of whiskey. It made it go down better than normal, it deepened the body and smoothed down the ethanol edges. I believe I came close to duplicating the oleogineous aspect of old whiskies that Mike and Chuck wrote about.
This whiskey - but not the imbiber - was well oiled.