E20 Petrol Can Damage Rubber Parts Of Fuel System In E10-Compliant Vehicles: Report

Last Updated:July 07, 2026, 10:20 IST

The study, which was a reference point for government as well as vehicle manufacturers on ethanol-blending issue, had stated that the parts affected by E20 “may need replacement”.

The ARAI report, which had recommended the rollout of E20 fuel, stated that after the fuel was used in E10-compliant vehicles, a deterioration was observed in the rubber parts of fuel-system components, like hoses, gaskets, seals and O-rings, according to The Times Of India.

The study, which was not made public but was a reference point for the government as well as the vehicle manufacturers on the ethanol-blending issue, had stated that the parts affected by E20 “may need replacement".

Engine Failure Observed In Some Cases

In its findings on the impact of E20 fuel on E10 vehicles, the study stated that during “4-wheeler engine durability test", the performance of one BS-IV engine was okay with E20 fuel, however, “issue was observed with BS-VI turbocharged engine after 265 hours of durability".

On the issue of engine durability, the study claimed that the test was carried out by two four-wheeler vehicle manufacturers, or OEMs.

In the test, one OEM did not face any issue in engine durability after 400 hours of testing, and its performance was acceptable with E20 fuel. However, in the other OEM, “thermomechanical failure of exhaust valve was observed in the engine(s) tested cumulatively for 809 hours", the TOI reported.

Also Read: ‘No Engine Damage, Marginal Mileage Changes’: Govt Issues 10-Point Clarification On E20 Ethanol Blending

A thermomechanical failure occurs when extreme heat and repeated mechanical stress combine to cause an engine’s exhaust valve to warp, crack or fracture.

However, people familiar with the findings said the exhaust valve failure observed in the second OEM’s tests may have been caused by factors other than the fuel, TOI reported.

Experts involved in vehicle testing also noted that engine durability tests are typically conducted for around 2,000 hours.

According to the report, engine durability tests carried out by three two-wheeler manufacturers found no issues, with the study concluding that the “performance is acceptable with E20 fuel".

No Adverse Impact On Vehicles’ Metallic Components

The study found that E20 fuel had no adverse impact on the vehicles or their metallic components across all models tested. It also said tailpipe emissions from E10-compatible vehicles running on E20 remained within the prescribed legislative limits.

The report noted that vehicles using E20 recorded a 2-6% increase in fuel consumption compared with those running on E10, although the extent of the increase varied across models.

It further found that evaporative emissions remained within the legal limits when using E20, while the vehicles’ startability and drivability performance were “ok with E20".

Ethanol Blending Backed By Scientific Studies: Govt

The government had on Friday pushed back against what it called misinformation surrounding India’s E20 ethanol blending programme, issuing a detailed 10-point clarification about engine damage, water consumption, vehicle warranties, fuel efficiency and environmental impact.

Also Read: ‘Ethanol Is Used In Racing Cars’: Oil Minister Defends Govt’s Biofuel Blending Programme

The Ministry of Petroleum and Natural Gas said the E20 programme, under which petrol contains up to 20% ethanol, is backed by scientific studies, regulatory safeguards and international experience.

The minister had also said that India’s ethanol blending programme is safe and dismissed claims that using E20 fuel could invalidate vehicle insurance policies.

The clarification came amid complaints from some motorists who have alleged reduced mileage, performance issues and engine wear with higher ethanol blends.

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Prisha Vibhavari

Prisha is the Chief Sub-Editor at News18.com, with more than 10 years of experience in national and international news. She specialises in editorial leadership, sharp news judgment, and high-impact st...Read More

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