If you use a chainsaw, electric or petrol, you use chain oil. This sticky oil is pumped into the groove of a chainsaw’s guide bar when the throttle is activated. The chain distributes it around the bar, providing essential lubrication and cooling. When the chain is running, oil is being pumped onto it and flung into the environment. Without that oil both chain and bar would fail very quickly.
A few years ago I bought a new Stihl 261, which has served me well so far. The chain oil reservoir cap sometimes doesn’t close securely if the tank is filled to the brim, and although usually I spot this, on a couple of occasions, I’ve picked the saw up and immediately noticed cap off and oil on the ground. The first time I despaired at the pollution it caused – one small patch of soil destroyed. Then I remembered the spill was bio-oil (oil derived from plant sources rather than mineral oil) used after working on a local authority site, so perhaps my action wasn’t quite so bad as first thought. My initial feeling of horror on pouring oil into the soil was misguided however.
During the course of a day’s coppicing – processing and cutting, I might throw (as a pretty modest estimate) two tanks of oil into the wood via the saw chain, without the slightest concern. That’s 0.54 litres of oil. I work in one hazel coppice on and off through any winter, so if I run the saw, say for twenty days (figure plucked out of the air), that’s over ten litres of oil dumped in the wood! I’ve been working this wood for fifteen years or so, so I must have deposited 150 litres of oil in it as well as others in the area. I immediately imagined taking seven, twenty litre containers and pouring them into a coppice coup amongst the flowers and grasses… don’t quote my figures but they are accurate enough to be horrifying.
Since then I’ve gone against most advice and bought bio-oil. In my experience, dealers and other users I know, turn their noses up at the stuff, suggesting that some unspecified horror will result from its use. I can say happily that five year’s hard work with my 261 sees it running sweetly, with no noticeable increase in chain or bar wear. The same is true of a Stihl electric saw I bought four years ago. I do keep a small amount of mineral oil in the workshop with which to soak chains, particularly before a lay off period. Whatever the producers say, bio-oil sets when left on a chain for a while and that’s not great for the saw.
Aspen suggest that “Because Aspen Bio Chain is biodegradable, it does not cause pollution of groundwater and sprayed oil is completely broken down once in contact with the soil flora. (Outboard Oil | Bio Chain Oil | Engine Oil | Aspen Fuel). One has to take these claims with a degree of wariness but it must be the kind of thing we should be wanting to hear. Bio oil is much more expensive than its mineral counterpart, but I feel strongly that we shouldn’t continue to chuck mineral oil – oil that will remain and accumulate – into the environment, cut after cut.