I got to spend last Sunday cutting firewood and clearing some unwanted cedar trees, and it was nice to get out in the woods again. Since I'm always looking for a back-up plan or just another way to do something, I did some digging into the oils a chainsaw uses.
2-Stroke OilMost chainsaws are powered by a 2-stroke engine that requires a fuel/oil mix. 2-stroke engines don't have an oil pan or internal lubrication system; the moving parts are lubricated by the fuel/oil mix passing over them on the way to the piston. Common mix ratios of gasoline:oil vary from 32:1 to 50:1, and there are many commercially available, petroleum-based oils to choose from.
Using more oil is always preferable to using too little. If you normally mix your fuel at 40:1, don't be afraid of using 32:1; it may smoke a bit more, but won't harm the engine. Going overboard on the oil will thicken the mix up to a point where modern carburetors won't pump it, but it won't harm anything.
My personal choice is OPTI-2, because I like the added fuel stabilizer and the simple packaging. Each pack makes one gallon and they fit in my saw case better than bottles... and there's less to carry back out as trash, too.
Older engines (pre-1970) were designed to run at lower speeds and used common motor oil (non-detergent 30W) in the fuel/oil blend at ratios of 20:1 or more. While motor oil might work on newer engines, it will likely cause excessive wear and shorten the life of the engine. Vegetable oils are the same: they will work for a short time but are not going to give the lubrication that the engine needs.
2-stroke engines are used in such a wide variety of applications that it is hard to get useful information on oils and substitutes:
- RC (radio controlled) airplanes use tiny 2-stroke engines with a high-energy fuel.
- Chainsaws and weedeaters use slightly larger engines and common gasoline.
- Certain racing motorcycles use large 2-strokes, as do snowmobiles and personal watercraft.
Bar/Chain OilChainsaws use a cutting chain that rides on a grooved bar. Since that is metal sliding over metal at high speeds, they need to be lubricated to ensure a useful lifespan. Commercial bar oil runs about $10-20 a gallon around here and is a thick, sticky oil designed to adhere to the chain and bar. Believe it or not, common rapeseed (canola) oil that you can buy in the grocery store has been tested and found to be a good substitute for petroleum-based bar oil. (Environmentalists got this research started by noticing that all of the oil being carried into the woods with chainsaws was being left in the woods; 2-stroke engines are “full-loss” lubricated, which means the oil used on the bar and in the engine was being “dumped” in the forests and that was just not acceptable to them.)
Europe being the mess it is, petroleum-based bar oils are now outlawed in Austria, and canola oils are the preferred substitute. Commercial blends here in the USA are more expensive than either grocery store canola oil or petroleum-based bar oil, but they are available. The US Forest Service published a Tech Tip article back in 1998 that covers the subject quite well.
Another benefit of using canola oil as a bar/chain lube is that it doesn't stain the wood, so if you are using a chainsaw to make lumber or furniture you won't have the problem of oil stains. It also washes out of clothing easier, and doesn't irritate the skin like petroleum-based oils can.
Pre-Mixed FuelI have seen quart cans of premixed 2-stroke fuel on the store shelves, but the cost was always higher than what it would cost to mix my own. $10.00 per quart equals $40.00 a gallon, whereas I can buy a gallon of non-ethanol gasoline for less than $3.00 and add a $3.00 package of oil to it. The only advantage the premix has is that they don't use gas station gasoline, and their high-octane base doesn't break down like normal gasoline and they claim a shelf-life of several years. One quart of fuel will run my saw for about an hour of moderate cutting, so I may have to invest in a few just to put aside for emergencies. Paying ten bucks for something that normally cost about a buck and a half is going to be hard, though.
Having a back-up plan for as much of my life as I can is the main part of prepping for me. I don't like to rely on single point of failure systems, redundancy is a lot more comfortable.