Leave the bar oil alone until spring

Don’t change to winter-weight bar oil just for storage. Decide that when you’re actually going to use the saw again.

Bar oil sits in a tank. It doesn’t burn, doesn’t get contaminated, and doesn’t go bad over a few months of storage. Winter-weight oil only exists to keep flowing in cold temperatures, and your saw doesn’t care about cold unless you’re running it. So putting thin oil in for the winter is busywork.

Come spring, look at what’s in the tank. If it’s still cold out, switch to a cold-weather bar oil or add some to thin things out. If it’s mild, just top off with your regular oil and cut. If the oil has gotten thick from sitting in an unheated shed, that’s normal—start the saw and let it warm up before making serious cuts.

Don’t overthink storage. Use the oil that matches the weather on the day you actually use the saw.

Final thought: The saw doesn’t know what season it is.