Concerns surrounding the use of E20 petrol in vehicles manufactured before 2022 have been widely circulated on social media, prompting panic among car owners. However, Ashwin Durai, a Chennai-based engineer, mechanic, and founder of ICD Tuning, has stepped forward to debunk many of these exaggerated fears.
In a detailed blog post titled ‘E20 Petrol in Pre-2022 Cars – The Truth Nobody's Telling You’, Durai, known as Madras Mechanic, draws on extensive workshop experience, race car tuning, and ethanol-based performance builds. He asserts that the majority of pre-2022 petrol cars, particularly those from the BS4 era, can safely operate on E20 fuel.
Debunking Engine Damage Claims
Durai argues that many viral claims about E20 petrol "destroying" engines often mistakenly attribute existing vehicle maintenance issues to ethanol. He highlights that most BS4 and newer petrol cars are equipped with electronic fuel management systems capable of adjusting to the E20 blend. Modern fuel systems, he explains, were designed with engineering tolerances that make the transition from E10 to E20 relatively minor.
Understanding the Fuel Economy Impact
While largely dismissing catastrophic damage claims, Durai's blog acknowledges one genuine downside: a reduction in fuel economy. Ethanol possesses less energy density than pure petrol, meaning drivers should anticipate a decrease in mileage. However, he challenges claims of drastic 30-50% mileage reductions, stating they are inconsistent with the fuel's chemical properties and real-world usage data.
In August 2025, the Ministry of Petroleum and Natural Gas, referencing studies by Indian Oil Corporation Ltd, the Automotive Research Association of India, and the Society of Indian Automobile Manufacturers (SIAM), clarified that E20 typically causes only a “marginal” 3–6% decrease in fuel efficiency for “older non-compliant” vehicles.
Managing Ethanol's Hygroscopic Nature
The blog post also addresses ethanol's hygroscopic nature – its tendency to absorb water. Durai advises vehicle owners to keep their fuel tanks full, particularly if the vehicle will be unused for extended periods in humid conditions. This practice helps mitigate the risk of water absorption and phase separation within the fuel. He clarifies, however, that this is primarily a concern for cars stored for weeks or months, not for those driven regularly.
Precautions for Older Vehicles
Durai concludes that owners of reasonably maintained BS4-era petrol cars should not panic about using E20. Nevertheless, he recommends additional precautions for owners of older BS3 and carburetted vehicles, as these are more susceptible to ethanol-related issues. For these specific vehicles, he suggests:
- Inspecting fuel hoses and seals regularly.
- Upgrading to ethanol-resistant components where necessary.
- Tuning carburettors appropriately for the new fuel blend.
- Avoiding long-term storage with E20 fuel in the tank.