When cutting firewood in the middle of the woods, sawdust mixes with the soil and chain oil ends up directly in the ground. Using a petroleum-based mineral lubricant under these conditions amounts to polluting the area with every refill. Making your own vegetable-based chain oil for a chainsaw helps reduce this impact while controlling the cost per liter, which is often much lower than that of commercial cans.
Viscosity and adhesion: what a chain oil must really do
Before mixing anything, one must understand what is expected from the lubricant. The chain spins at very high speed around the guide. Without a sufficiently thick oil film, metal rubs against metal, the temperature rises, and the guide wears down in just a few hours of intensive work.
Two properties matter more than all others: viscosity (the fluid’s ability to remain thick under heat) and adhesion, sometimes referred to as “stickiness.” An oil that is too fluid is ejected by centrifugal force before it can lubricate anything. An oil that is too thick does not circulate properly in the lubrication circuit and blocks the pump’s flow.
Raw vegetable oils fall within a viscosity range close to what a chainsaw requires, but they are not all equivalent. Rapeseed oil, for example, offers superior natural adhesion compared to sunflower oil. This is why it is commonly used as a base in most homemade recipes and in several biodegradable commercial products like CHAINBIO from RatioParts or YORK 650 BIO.
One can make an effective chain oil for a chainsaw as long as this viscosity requirement is met, which immediately rules out lightweight cooking oils like grape seed oil or liquid coconut oil.
Vegetable chain oil recipe: rapeseed base and adjustment of stickiness
The simplest formulation is based on virgin or semi-refined rapeseed oil, available in agricultural cans of several liters. Rapeseed offers a good compromise between lubrication, cost, and availability in France.
Base mixture
- Rapeseed oil as the main component (at least three-quarters of the mixture), for its natural viscosity and adequate lubricating power at room temperature.
- Castor oil as a supplement (about the remaining quarter), which provides a significantly higher stickiness than rapeseed alone and improves adhesion on the guide at high speeds.
- No chemical additives are necessary for regular use in domestic logging. The anti-wear additives found in commercial oils are mainly useful in intensive professional logging.
Adjusting for the season
In cold weather, rapeseed oil thickens and the pump flow decreases. One can slightly increase the proportion of refined rapeseed (less viscous than virgin) or add a small amount of sunflower oil to thin the mixture. In summer, the opposite problem arises: the heat makes the mixture too fluid. This is compensated by increasing the amount of castor oil.
Feedback on this point varies depending on the machines, as the oil pump flow differs from model to model. On a chainsaw with an adjustable pump, the flow is adjusted rather than the recipe. On a fixed-flow model, it is the viscosity of the mixture that does all the work.
Concrete limits of homemade vegetable oil in the field
Homemade oil works, but it is not perfect. Ignoring its weaknesses can lead to costly disappointments with the equipment.
Rancidity is the first problem. Unlike mineral oil, which can last for years, vegetable oil oxidizes. A can of rapeseed-castor oil mixture left for six months in a garage can become sticky, acidic, and clog the lubrication circuit. Therefore, small quantities are prepared, to be used within the following weeks.
The second point concerns resin. On conifers (pine, spruce, Douglas fir), the sap rich in terpenes mixes with the vegetable oil and forms a sticky deposit on the guide and in the chain groove. Cleaning the guide after each cutting session on conifers becomes necessary, whereas mineral or synthetic oils resist this phenomenon better.
The third factor is regulatory. Since decree n° 2024-316 of April 5, 2024, the terms “biodegradable” or “ecological” can no longer appear on a product without justification by an official label such as the EU Ecolabel or NF Environment. Homemade oil remains perfectly legal for personal use, but it cannot be sold or distributed as “biodegradable” without certification.
Storage and maintenance of the lubrication circuit with vegetable oil
The lubrication circuit of a chainsaw was not designed for food oil. A few precautions can prevent breakdowns.
- Empty the oil reservoir if the machine remains unused for more than two weeks. Stagnant vegetable oil can polymerize and clog the fine conduits of the pump.
- Filter the mixture before filling through a fine cloth or coffee filter to retain impurities from the raw rapeseed, especially in agricultural cans.
- Clean the guide groove and the oil outlet at the end of each cutting day with a flat screwdriver and a cloth soaked in household alcohol.
- Store the mixture in an opaque container, away from light and heat, to slow down oxidation.
An opened can of vegetable oil lasts a maximum of three months under good conditions. Beyond that, it is better to send it to compost or recycling at a waste disposal site rather than risk clogging the pump.
Making your own vegetable chain oil remains an accessible process for any occasional chainsaw user. Rapeseed does most of the work, castor oil improves the hold on the guide, and careful storage compensates for the lack of industrial additives.
For those who cut several steres per year or regularly work with conifers, a certified biodegradable commercial oil will be more suitable in the long run. The basic principle remains the same: protect the guide and the chain without contaminating the soil.
