MN is -40 DEC/JAN So leave it alone, Don't add additives unless you leave the State, The Glow plugs that VM uses are NOT sufficient in -25 or Colder I would plug in at that point, Just like Most HPCR starting in extreme cold generally no problem. If you plan on Keeping the VM3.0 I would remove the Glow plugs ASAP and use heat Never seize, They like to fail after years of use and if they break off when removing to replace the head in many cases needs to be remove to get them out. The EPA in its lack of wisdom considers the Glow plug to be AECD so if they fail you will need to replace them or you will eventually deal with derated Power. I hope you have done your research, The VM 3.0 is fear by most shops around here and Many Dealer Techs hate the motor even more, Some refuse to work on them.