im not saying do it by anymeans, saws are designed to run out of fuel and have 1/4 tank bar oil left to ensure the bar/chain stays lubed, and used oil would run out way faster, on the flip side, oil is oil, and in the winter you want to run a thinner bar oil in the winter to ensure the bar/chain is properly lubed. like i said echo is on the thin side, and husqvarna offers a winter bar oil, now i doubt youll find it @ lowes, etc, but a servicing dealer SHOULD stock it