Usually, the components of lubricants are divided into base oils and additives. Additionally, lubricating greases contain a certain amount of thickening agents. As a rule of thumb, it can be assumed that biodegradability is determined by the base oils and the toxicity is determined by the additives. The environmental properties of thickening agents tend to vary significantly.
Additives are often sold in packages. In most cases, this means that the package consists of a number of substances that all have their own specific functions. Such a package may, for instance, contain corrosion inhibitors, extreme pressure additives, dispersants and an antioxidant.
The base oil, too, may consist of a combination of substances in order to reach the desired viscosity. Base oils are commonly divided into mineral, vegetable and synthetic oils. The drawback for biolubricants is that (in market statistics, for instance) no distinction is made between types of synthetic base oils, i.e. whether they have been manufactured from mineral or vegetable oils.
Either type of oil may have excellent biodegradation and toxicity performance, but when it comes to sustainability, in terms of using renewable materials, a synthetic base oil manufactured from vegetable oil will often outperform a synthetic base oil manufactured exclusively from mineral oil.