Impact of Low-Quality Diesel on Diesel Engines: Explanation from UGM Expert

JAKARTA, KOMPAS.com – PT Pertamina (Persero) has once again adjusted the prices of non-subsidised fuel oil (BBM), effective from 4 May 2026. Several products have experienced increases, particularly high-octane fuels and diesel. The most significant rise has occurred in diesel-type fuels, with Dexlite increasing from Rp23,600 to Rp26,000 per litre, and Pertamina Dex from Rp23,900 to Rp27,900 per litre. Not all products have changed. The price of Pertamax remains at Rp12,300 per litre, Pertalite at Rp10,000 per litre, and subsidised Biosolar still at Rp6,800 per litre. Amid these price changes, questions have arisen regarding the impact of using low-quality diesel on the performance and lifespan of diesel engines. Lecturer from Gadjah Mada University (UGM), Jayan Sentanuhady, explains that using low-quality diesel, often referred to as ‘rotten’ diesel, can directly affect the decline in diesel engine performance. The engine feels heavier to accelerate, the response slows down, and combustion efficiency becomes suboptimal. This performance degradation occurs because the content in low-quality diesel generally does not burn completely. As a result, residue forms that can deposit in the combustion chamber as well as important components such as injectors and fuel filters. In the long term, he said, this condition makes the engine work harder and accelerates wear on components. Not only that, maintenance frequency becomes more frequent because the fuel system becomes dirtier more quickly. Another equally important impact is the increase in exhaust emissions. Low-quality diesel tends to produce thicker smoke and higher pollutant content, thus contributing to air pollution. Therefore, fuel quality is a crucial factor that cannot be ignored. In addition to affecting daily vehicle performance, choosing the right diesel also plays a significant role in keeping the engine lifespan optimal.