You've got your skin-care regimen on lock: serum night cream . But what if we told you that your skin would benefit even more with the addition of one product? That product is a face oil, and we even have a magic ball that will tell you exactly which one you should spend your hard-earned cash on: Rank & Style gives the lowdown on the oil you need to pick up on your next beauty shopping spree.The site uses customer reviews, editors' picks, and overall buzz to figure out which products are going to work the hardest for you. (Consider its authors beauty lovers with a penchant for math.) After crunching the numbers, Rank & Style has named Kiehl's Daily Reviving Concentrate the clear-cut winner.This little bottle wins for a few reasons. It's garnered some major buzz and is also a top pick among editors. Plus, the reviews are rad. On Nordstrom, user Allanouthtefact says, "This was so light and absorbed so quickly. It left my skin hydrated without appearing greasy. Perfect for the winter weather." With the temperatures dipping, that's nothing to shrug at.So, even if you've been hesitant about trying a face oil, consider this Kiehl's option. Giving yourself an extra bit of glow may be exactly what you need during the gray days of winter.Daily Reviving Concentrate, $46, available at Nordstrom