I have a Simplicaty snowblower that has sat for two years with oil that was changed two years ago. It was changed with Dino Shell 5w30 after the last storm we had two years ago so if I use this snowblower this year do I need to change it again? It looks just as clean as the day I put it in. I used my old Toro for the last two years but I want to use my Symplicaty this year. By the way it's a good size two stage with a good size B&S motor the unit is aprox 6 years old.