As with many things in life, supply and demand can dictate terminology and opinions. There are many buzzwords and marketing stances regarding eco-friendly lubricants and many are misleading or can exploit two worthy efforts - (1) Protecting our environment; (2) Finding renewable sources.
There is an old Native American proverb that states, "We do not inherit the earth from our ancestors, we borrow it from our children." There are no universally accepted definitions for environmental safety, but much work has and continues to be done with measuring factors such as biodegradability, eco-toxicity, and renewability.
Measuring Biodegradability in Environmentally-Friendly Lubricants
Biodegradable means the degradation of the fluid in the presence of micro-organisms (bacteria). There are two widely accepted measurements. The first is primary, which measures the reduction of the carbon-hydrogen bonds. The Coordinating European Council (CEC) initiated their test L-33-93 to measure this over 21 days. The second is ultimate biodegradability and measures the evolution of carbon dioxide from the degradation over 28 days by the Organization for Economic Cooperation and Development (OECD) 301B/ASTM D5864. The CEC qualifies a lubricant as biodegradable if more than 80 percent degrades, and OECD is more than 60 percent.
Alternative Oils Have Shortcomings
The use of vegetable oils such as canola (rapeseed), soybean, and sunflower is not new technology. These were widely used during both world wars much like rice hulls and corn husks were used to make rubber. They have some advantageous inherent qualities, namely great lubricity, high viscosity index, and high flash points. There are also some significant shortcomings. These fluids have inferior oxidation and thermal stability, higher pour points, and degrade more readily than mineral based fluids. They are triglycerides, so they have fatty acids connected to glycerol. When these fluids degrade, these fatty acids basically make grease or plastic-like residues and also can play havoc on fluid recycling. So here comes the obstacle for these fluids being truly eco-friendly - additives are needed to correct their shortcomings. Most additive technology is yet to advance to eco-friendly status, with much of it having minimal potential to get there.
While advancements continue to be made, we remain at definitions that are loose and test methods that accept 60 or 80% as measuring sticks. Machinery Lubrication cites that of 2.5 billion gallons of lubricants sold annually in North America, nearly 60% are not accounted for after use. It could be concluded that the efforts of all should be focused on (1) eliminate the disposal of lubricants into the environment; (2) prioritize efforts to develop and use environmentally safe products in environmentally sensitive applications.