What a hilarious and cute little game! I didn't play for too long but for the short time I was in, it was such a nice experience!
My biggest loves of this game is the simplistic music, and sound design you have in the game. The art direction is simple and works well. The game loop is quite simple and works good! Plow the snow to get money, use money to refill yourself. Sustain.
I think you should look into adding obstacles that attempt to break the loop, that will add some tension. Such as obstacles that will drain your fuel?
My biggest gripes was it can be difficult to plow snow directly beneath you. I think it should be fine to have the tractor move above the snow but consider a way to intentionally dig beneath you to plow better.