What are biolubricants? All you need to know about biodegradable oils

Biodegradable lubricants are part of the transition towards more environmentally friendly industrial operations. In recent years, biolubricants have gained weight, as they allow working with technical guarantees while reducing the environmental footprint when there is a risk of leakage in sensitive environments, such as the sea or the forest floor.

In this guide, we will explain what biodegradable oils are and some key aspects about them, such as how to measure their biodegradability or the certifications that accredit them.

What is a biodegradable lubricant or biolubricant?

A biolubricant is a lubricant formulated to degrade in the presence of microorganisms. It can come from renewable raw materials or of fossil origin, but what defines it is its behavior in the face of biodegradation.

However, it must be taken into account that a lubricant can degrade and still be problematic if it affects aquatic life or concentrates in tissues over time. That's why a biolubricant must add two other essential principles: it prevents ecotoxicity and bioaccumulation in organisms. In addition, certain substances with hazard indications are restricted or directly excluded: they must not be intentionally added or formed in the final product.

The objective in the formulation of lubricants is clear: to reduce persistence, toxicity, and accumulation, without sacrificing the main function of the lubricant. Of course, they should not be confused with "bioproduct", a label that refers to the renewable origin, without necessarily implying biodegradability. Origin and behavior are related concepts, but not equivalent.

How biodegradation is checked

The OECD 301b test

Biodegradability is assessed in standardized tests that give manufacturers and operators a common language to help them decide. In lubricants, the most widespread is OECD 301b, which measures the carbon dioxide generated by the decomposition of the product and compares it with the theoretical maximum possible in a controlled atmosphere (i.e., without carbon dioxide).

With this framework, a substance receives the label of "readily biodegradable" when it reaches 60% of the theoretical maximum in 28 days. When the degradation exceeds 20% but does not reach 60% in that period, it is considered "inherently biodegradable". And if it does not reach these thresholds, it is classified as "non-biodegradable".

The Ecolabel and other seals

Biodegradability certification labels integrate environmental and performance requirements, so they are also a way to improve standardization and make it easier for customers to choose. In Europe, the reference is Ecolabel, but there are also other important ones, such as Blue Angel, EAL, or Nordic Swan.

All of them value biodegradability, the absence of bioaccumulation, ecotoxicity, and substance limits, together with a minimum performance in service.

How to choose a biolubricant

When choosing a biolubricant, the practical recommendation involves comparing certifications and reviewing technical and safety data sheets to verify tests such as OECD 301b and ecotoxicity results.

Without going into too technical aspects, you should also bear in mind that biodegradability is born in molecular design. In general, more linear structures are more accessible to microorganisms. However, thermal and oxidative stability - key in many machines - can be stressed with this ease of degradation.

That is why lubricant bases are crucial for this task: oils of vegetable origin and certain saturated esters offer high biodegradability and renewability, but require attention to hot stability, hydrolysis, and compatibility with elastomers. On the other hand, the mineral bases of Groups I–III and PAO stand out for their thermal and oxidative robustness, with very low biodegradability.

Therefore, choosing well is to balance stability and biodegradability depending on the equipment, the working temperature, the planned maintenance, and, above all, the environment. When the medium is close, biodegradability and the absence of bioaccumulation weigh more. On the other hand, if the thermal demand is extreme and the environmental risk is low, the stability can become more important.

In both cases, deciding with data is the best guarantee. If you want to compare the needs of your equipment or installations, we can help you translate environmental and operational requirements into practical decisions. Just fill in this form and our technical team will contact you.