These specials do not fit regular spouts. Labels or trademarked closures make these more desirable. Oil bottles were in use from the 1910's to 1950's. The WW II specials were, of course, from the 1940's. The age of the bottle can sometimes be determined by mold marks on the base.
Some bottles have two digits that can designate the year.
Often it is only the last digit of the year. For more information on these technical points contact a local antique bottle club through the Federation of Historical Bottle Collectors . Most oil bottles were embossed with the oil company's brand or the retailer's name. Collectors should be aware that some unscrupulous persons have put decals on plain bottles and sell them as if they were original fired-on color logos. Original color does not scratch easily.