I use Optilube XPD in 3 duramax's with 50% #1. No problems and it was COLD this past January.
I have a bottle of Hot Shots setting on the same shelf. I will not use it now in the winter. When it was -14°F last month, it was just as thick as honey.
I use Howes in the farm equipment, but that stuff doesn't get used in the extreme cold, except for the skid steer. No problems with it.