I'm sure the Pennzoil Platinum would be fine. At least you change and check your oil, unlike most guys I know who would run 10 year-old tar in -40 degree conditions.
For my outdoor equipment engines, I prefer a heavy duty engine oil with extra zinc, etc. My opinion is swayed by what I have read over the years on this site with regard to "best" oil for air cooled, hard working engines like my snow-blower, pressure washer, your welder, etc. The price of the Devlac 0W30 is outstanding, so it's a no-brainer for me.