BRIN Warns of Water and Sludge Risks in B50 Biodiesel, Urges Users to Tighten Maintenance

Jakarta — With B50 on sale at every fuel station since 1 October 2026, the National Research and Innovation Agency (BRIN) has warned that a 50% biodiesel blend carries technical risks that differ from those of pure diesel. Users, particularly those storing large volumes of fuel, are being urged to tighten fuel receipt, storage and maintenance procedures.

Hygroscopic properties at the root of the problem

Maharani Dewi Solikhah, coordinator of BRIN's Biofuel Research and Development Group, explained the issue at a discussion on the impacts of, and solutions for, using B50 biodiesel (Biosolar). She said the FAME component readily absorbs water. Absorbed moisture can encourage microbial growth, corrosion and sludge deposits that risk clogging fuel filters.

Continuous exposure to air and water also accelerates oxidation, producing acidic compounds, polymer deposits and sludge. Because FAME is an ester, it is more prone to degradation, and B50 has a lower calorific value than diesel. On the other hand, BRIN noted that Indonesian biodiesel refined in line with Ministry of Energy and Mineral Resources (ESDM) requirements has an oxidation stability of more than 13 hours and, as an oxygenated fuel, can deliver better emissions.

BRIN also highlighted the long distribution chain in an archipelagic country, spanning trucks, ships, pipelines and rail. Careless handling at any link can degrade quality before the fuel reaches users. In addition, biodiesel's solvent properties can loosen old deposits in fuel lines, which then collect in filters.

Advice for users

• Tighten fuel receipt procedures and ask suppliers for a test result report (Laporan Hasil Uji, LHU).
• Carry out preventive maintenance on storage systems.
• Make sure tank materials are compatible with biodiesel to avoid corrosive reactions.
• Check that FAME content matches the specification.

The B50 specification itself is described as stricter than B40's: a higher cetane number, a lower maximum water content, and tighter cleanliness and particulate criteria. Technical handling and storage guidelines are being drawn up by BRIN together with the Ministry of Energy and Mineral Resources; the B40 version can already be downloaded, while the B50 version is still awaiting approval. Quality standards are discussed in Biodiesel Quality Standards.

Government claims and user complaints

The government has offered a more reassuring picture. At a hearing with Commission XII of the House of Representatives (DPR) on 8 September 2026, Eniya Listiani Dewi, Director General of New, Renewable Energy and Energy Conservation (EBTKE), cited road tests of up to 50,000 km. According to detikOto, filters that are normally replaced at around 10,000 km did not need changing until 37,000 km. Mining trials at three companies over roughly six months, according to a Koran Jakarta report citing Antara, found that engine filters usually replaced at 250 hours lasted up to 500 hours. Gaikindo and several associations are continuing tests up to 100,000 km.

However, members of Commission XII, as reported by Koran Jakarta, also raised user reports of filters needing more frequent replacement and of a need for additives. Those reports did not specify numbers, locations or vehicle types. Meanwhile, Mars Ega Legowo Putra, President Director of Pertamina Patra Niaga, said the company's customer service centre had not received any significant complaints from retail users.

These differing accounts show that long-term field data is still pending. Results of the 100,000 km test have not yet been published.