Today, if you talk about a “Bio-lubricant” or “EAL” the prefix “Bio-“ is linked to many different aspects of lubricants, as shown in Figure 2. This situation does not help to develop the market potential of these lubricant products as it is confusing for customers who need a clear, transparent and under-standable definition of what constitutes “bio-lubricants”.

The approach of CEN TC19/WG33 When in 2009 the CEN TC19/WG33 standard set out a definition of the wording “bio-lubricant”, the philosophy was not to compete with existing ecolabels but to supplement them by supporting customers in the market with a working, universal definition based on a set of verifiable properties of the finished product.

Customers cannot look inside the formulations or approval processes of finished lubricants. However, if necessary, they should have an opportunity to check ecotoxicity and the performance of “bio-lubricants” for their own purpose.

The accompanying technical report TR 16227 [4] to the standard, proposed a tool kit of easy-to- handle and reasonably priced tests that could be used to provide proof of the renewable content, biodegra-dability, aquatic toxicity and technical performance characteristics present in a lubricant. This proposal has finally been transformed into a set of requirements in the finished definition standard EN 16807[5]. But the question remains whether it is possible to test finished products based on this set of tests?

Finally the technical performance of the final product can only be tested on finished lubricants. So, to put the standard EN 16807 that defined ‘’bio-lubricants’’ into practice, biodegradability has to be determined. All existing test methods for mineralisation are developed for substances only. Non water-soluble substances need special processes by which they are tested, reducing the precision of the test even more. It has therefore been a challenge to develop a test method based for mineralisation which could fill the gap of testing finished ‘’bio-lubricant’’ products to a sufficient level of accuracy.

Figure 4.

The standard EN 17181 [6] attempts to resolve this issue by adding another test to the tool kit for finished lubricants. This standard has been developed using the OECD (Organisation for Economic Co-operation and Development) 301 B standard as a basis, and includes several improvements in test procedures to increase the precision of the result. Its ILS in 2016/2017 is based on 8 lubricant samples and tested in 9 laboratories and presents the latest precision data since the late 1990s. [7].

Figure 5. Figure 3.

Beside the test for renewable content under ASTM D6866 and of the aquatic toxicity tested under EN ISO 8692/6341/ 7346-1, both well established and applicable for fully formulated products, biodegra- dation should be tested using test methods EN ISO 9408/99439/14593.


With a reproducibility of ~ 36% precision of EN 17181 the improvement compared to test methods such as ASTM D 5864 (R: max. 42%) seems to be small. However, it must also be taken into considera- tion that an increase of both test laboratories and of test samples does not necessarily improve the precision of the test itself.

Two examples of test results demonstrate the variance of results depending on sample and laboratories.

Continued on page 38

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