Don't use marine 2 stroke oil in your chainsaw!!
Unfortunately, we learned this the hard way.
My father called me at work to ask me what brand of chain saw got good ratings. I googled a few of the model numbers he gave me and came up with one that was decently rated with a decent price. He asked me to find out if it had an automatic chain oiler or not. In reading the online owners manual, I saw it said in large capital letters, "DO NOT USE MARINE OIL IN YOUR CHAINSAW!" I said, well hmmm, that's different, I thought 2 stroke oil was 2 stroke oil. I was wrong.
2 stroke marine oil is formulated for marine engines that are water cooled and operate at a much lower temp than air cooled chainsaw engines. Thus, their protection breaks down at high temps. You may use a TC-W3 oil but it must be the TM designated oil, which says its approved for air or water cooled engines. Otherwise, use ONLY API TC rated oil.
I know, since I was a little boy, my father would just pour some of his 2 stroke outboard oil into his chainsaws and he ALWAYS had issues with chainsaws and now he needs another one after using his brand new one only a few times, saying the engine is shot. I think I discovered why. I made sure he realized, in no uncertain terms, that he will keep buying new saws as long as he keeps trying to save money and use outboard oil in a chainsaw.
I wanted to pass this along to everyone, do not use outboard oil in your saw! Use the oil in the little bottles with the picture of the chainsaw on it. IT DOES MATTER.