I've got an old Homelite saw that leaks oil if you leave it in the tank. I'm convinced this saw is our answer to the oil crisis. If I leave an ounce of oil in it, it'll leak out a gallon. /forums/images/graemlins/crazy.gif Best solution is to just drain it when done.
A couple summers back, I bought a new Stihl MS260. It doesn't leak a drop. I always fill it when ready to store away.
(I keep the old Homlite on hand for when my favorite Bro-In-Law wants to borrow my chainsaw! /forums/images/graemlins/wink.gif It NEVER wants to start, the chain is worn out, burns way too much gas, and needs a new spark plug every time he uses it.) (Plus, he always brings this one back. I have to go after the Stihl when he used it)