(Xinhua) Quality watchdogs in Hainan Province said they have sent gas samples for tests after receiving complaints about cars stalling after using oil from China's largest oil refiner.

Drivers were waiting outside a gas station owned by China Petroleum & Chemical Co in Haikou City yesterday morning, demanding compensation for the damage the oil has caused to their cars.

The drivers said they consulted their car dealers and mechanics found it was the oil that caused clotting in fuel systems.

One mechanic said he had fixed 23 vehicles with the same problem.

The new quality complaints came weeks after China Petroleum, also known as Sinopec, apologized for a quality lapse in its gasoline products that damaged thousands of cars in central China's Henan Province.

But a May 7 statement issued by Sinopec denied it has any connection with cars stalling. It said the gas products used in Hainan were from the same batch used in Guangdong Province and Hong Kong, and no problems were reported in those areas.

The number of damaged vehicles would be in the thousands if there was something wrong with the gas products, yet only dozens of drivers have reported shaking and stalling with their cars.

An official with Sinopec's Hainan office said if the tests prove the company is at fault, it will pay compensation for all damage. He added that was improbable because the company tested the gas products in Hainan and found no quality issues.