Someone told me that you can use motor oil in your chainsaw instead of bar oil. Is this a good idea? Will it cause problems over time?
It might be OK for a bit but I probably wouldn't do it. You could look up your owner's manual to see if they say anything. If you must use the chainsaw and have nothing else on hand, surely motor oil is better than nothing. I think bar oil is stickier than regular motor oil to prevent splattering as much.
FWIW I like to buy the "biodegradable" chain oil, since it invariably ends up all over the place.
you shouldn't run anything but bar oil on a chainsaw bar, but not because of the saw (even though it sticks better to the bar and lubricates the chain better). its the environment and your lungs. engine oils usually have one or two zinc thiophosphate compounds added into them. its not good for you to breathe this in in aerosol form (like grinding galvanized metal), but then again, its not good to breathe it in in after combusting in an older engine that burns oil. the two stroke oil your saw uses in the fuel mix doesn't have this additive
You will spray motor oil everywhere, and you will run out of oil quickly, and then burn up the bar and chain.
That being said, I sometimes use a mix of bar and gear oil or motor oil in winter, when it's so cold outside that the bar oil won't flow quickly enough. On such days, I would only mix about 1 part motor oil with 10 parts bar oil (or 1 part gear oil with 5 parts bar oil). The saw will warm up eventually and the oil will flow faster, so I only do that for the first tank of oil.
I have a Ryobi 40v electric, which isn't a "real" chainsaw (it has a much slower chain speed), but 30w works just fine. I haven't had any splatter or mess, and it's cheap. My chain doesn't seem to be stretching more than expected. I mention it because more and more homeowner types will be moving to the new breed of electrics as they continue to improve.
I figure if it's suitable for engine parts moving at many times the speed and force of a saw chain, it's good enough for a saw chain. Those working in biologically sensitive situations actually use vegetable oil with decent results. The issue is fling. Actual bar oil is in the neighborhood of 140w.
My concern with used motor oil would be that used motor oil has all kinds of contaminants from the crankcase that would be just terrible for your lungs (oil mist) and the environment. Nasty things like lead from the bearings, chromium, etc. No one in their right mind would want to dissolve that toxic soup into a mist they're going to toss into the air around them.
I suppose it depends on your definition of OK. Will the saw explode the second you run it? No, but if your unit is under warranty then the manufacture sure will deny any warranty claim if they can determine that the wrong oil was used.
All motor oil is not equal either as it comes in varying viscosities and types. Sticking with "bar oil" will ensure you are using a product designed specifically for this purpose. Likewise you should ensure you mix the appropriate type of oil with your gasoline or just buy the pre-mixed stuff and not worry about it.
I have a high-end Sears electric chain saw that is about ten years old. The quality of the saw seems unattainable today, and was recommended by a Stihl dealer when I bought it. I have used drain oil from my antique cars, exclusively in the saw, with no ill affects. Tends to be 30wt. or 20W50 and have about 1000 miles on it when drained.