Many generator manufacturers recommend a 5W for cold starts 32 below I don't see an issue with your choice. Modern Generacs use 5W20 year round they're living dangerously or what lol?I tried to pull-start my generator when it was -5 degrees with 10W-30 in it, and it was really hard to pull thought I was going to break the cord. Drained the10W-30 out after the power came back, refilled with 0W-40, it pulled a lot bettera few days later a 0 and I never used anything else. It has been used for days at a time, winter and summer. 0W-40 or 0W-30 for peace of mind.