I've never added anything to the fuel this winter or the one last year. The coldest tempurature I saw this year was around -25 °C. The coldest one I saw last winter was -30 °C. Both times my Cruze started just fine. There's Esso stations in my area I use to fill up with Diesel. The station's fuel seems to be fairly well managed and used enough that I haven't had any gelling issues.