Unpublished ARAI Report Flags E20 Impact On E10 Vehicle Rubber Parts

An unpublished study by the Automotive Research Association of India has found that E20 petrol causes deterioration in rubber fuel-system components fitted to E10-compliant vehicles, claims a new report by The Times of India. The affected parts include hoses, gaskets, seals and O-rings.

The ARAI had earlier recommended the rollout of E20 fuel. The report has since served as a reference point for the government and vehicle manufacturers on ethanol-blend compatibility, though it has not been released publicly. The report recommended that the affected rubber components may need replacement in E10-compliant vehicles running on E20 fuel.

A car being filled with fuel. Image Source: PTI

Engine Durability Tests Show Mixed Results

The ARAI report's four-wheeler engine durability tests produced mixed results across two original equipment manufacturers, per the Times of India. One OEM ran a BS-IV engine for 400 hours on E20 fuel without any durability issues, with performance rated acceptable throughout the test.

A second OEM recorded a thermomechanical failure of the exhaust valve after the engine had been tested cumulatively for 809 hours. A thermomechanical failure occurs when combined thermal stress and repetitive mechanical movement causes an exhaust valve to warp, crack or fracture.

The report also noted a separate issue with a BS-VI turbocharged engine after 265 hours of durability testing. People aware of the findings told the Times of India that other factors could have contributed to the second OEM's exhaust valve failure.

Engine durability tests are typically carried out for 2,000 hours, making the shorter test durations a relevant factor when interpreting the results. Durability tests conducted by three two-wheeler manufacturers found no issues, with performance rated acceptable on E20 fuel across all three test vehicles.

No Impact On Metallic Parts, Fuel Consumption Rises 2-6%

Across all vehicles tested, the unpublished study found that E20 fuel had no adverse impact on metallic components. Tailpipe emissions on E20 remained within the legislative limits set for E10-compatible vehicles, and evaporative emissions also stayed within the prescribed limits.

Startability and drivability performance across all the tested vehicles were rated acceptable with E20 fuel. However, fuel consumption on E20 rose between 2% and 6% compared to E10, though the increase varied by vehicle.

India has already transitioned to 20% ethanol blending in petrol nationwide, half a decade ahead of the government's target. The findings of the unpublished ARAI report add fresh detail to the ongoing debate over E20 compatibility with older E10-designed vehicles, a discussion that has intensified in recent days following a host of statements and clarifications from both the government and multiple automakers following intense social media criticism of the blended fuel.