DIAGNOSIS That’s almost certainly bar and chain oil leaking from the reservoir through the oiling port. It’s a known quirk with this and many other saws. The oiling system is simple and gravity-fed, so if the saw is stored in certain positions, oil will slowly seep out.
FIX The storage position is key. Always store the saw with the bar and oil tank cap facing upward. Don’t lay it on its side, and definitely don’t store it with the bar pointing down. If you’re storing it long-term, it’s best to just empty the oil tank completely. Run the saw for a few seconds without cutting to purge the oil lines, then drain any remaining oil from the fill hole.
IF THAT DIDN'T WORK If it’s a significant leak even when stored upright, check the oil tank cap o-ring. It can get pinched or damaged, breaking the seal. Also, look at the bar pad area where the bar mounts. If oil is coming from there, the internal oil pump diaphragm might be faulty, but that’s less common than simple seepage.
HEADS UP That oil is biodegradable bar and chain oil, but it’s still a messy, slick substance. Put a piece of cardboard or a drip tray under the saw where you store it. Never store it on a concrete floor where the oil can stain, or on a wooden shelf where it could be a fire hazard if it soaks into something combustible.