Officials from the Ho Chi Minh City Department of Science and Technology put the seals on 30,900 liters of substandard gasoline July 21 they found being sold at filling stations in the city.
Department official Nguyen Thi Thanh Nga said seven out of 10 samples failed to meet the prescribed octane rating of 92 RON.
Among the errant filling stations were Thanh Tan on Tan Ky Tan Quy Street, Binh Tan District; Dong Thanh in Hoc Mon District; and 61 Tran Hung Dao Street, District 1.
They were found to mix other fuels, including A83, with A92 gasoline.
The department will fine them VND5 million-8 million for the violation.