Sinopec, on Tuesday, announced the results of its investigation on the 93-octane gasoline which has been the source of many complaints that caused car engine damage in three cities in Henan Province since late March.

Tian Zhongshan, general manager of Sinopec's Anyang unit, publicly apologized to customers for this serious breach in quality resulting from Anyang’s poor quality inspection and operation mistakes.

The result shows that 93-octane gasoline at the company's gas stations in three cities in Henan contain solvents at 34.0 milligrams per 100 milliliters, higher than the national standard of 5 milligrams per 100 milliliters, and contained 0.022 grams per liter of manganese additive, higher than the state standard of 0.018 grams per liter.

Officials related to the case have been suspended from duty and are under investigation, according to an insider from Sinopec.

Sinopec has worked out detailed compensation for customers and deal with any problems related to the gasoline. All cases are expected to be dealt with and completed within half a month.

From late March, customers in Henan's Xinxiang, Anyang and Jiaozuo complained that their vehicles had trouble starting, while others had red or black liquid spilling out of the vehicle after filling up with 93-octane gasoline supplied by Sinopec.