India, Aug. 6 -- Complaints about E20 petrol, mandatory at Indian fuel pumps since April, have run for months. The disquiet has been largely on social media, but in recent weeks, two industry letters have given it technical weight. On July 24, petrol pump dealers wrote to the Centre saying they can test dispensed fuel only for density and water paste - alluding to an inability to test for humidity that has become a unique Achilles heel for fuel stocks that can spoil. Days later, the Society of Indian Automobile Manufacturers (SIAM) flagged chloride and moisture contamination as damaging vehicle components, then withdrew the letter within hours of it becoming public, citing a need to authenticate the readings. The government has answered b...