Twenty-four Coles Express and between 25 and 30 BP service stations across Victoria temporarily stopped their gas supply as a result of its compromised quality.

Caltex service stations, which have some of their LPG supplied by Shell, were also affected.

The Shell Company of Australia has taken responsibility for the bad gas and says it will compensate customers. Heathcote resident Sharon Ettwell is one of almost 30 LPG customers to book her car into Bendigo’s Gejay Automotive after her car was damaged by the contaminated gas.

Ms Ettwell has been told it will cost more than $1000 to have her car fixed.

"My car was running perfectly until Monday," Ms Ettwell said.

"(Then) It wouldn’t drive over 60 (kilometres per hour).

"I put it immediately onto petrol and it was fine."

Shell spokeswoman Claire Wilkinson confirmed there was a quality issue with a batch of LPG supplied to some retail outlets in Victoria from its LPG depot at Lara, near Geelong.

"This quality issue related to higher than normal residue levels in the LPG," Ms Wilkinson said.

"Shell regrets that some motorists who purchased the affected LPG have experienced operating problems with their vehicles, including difficulties in cold starting and rough running.

"As soon as this problem was identified, Shell stopped supplying LPG from Lara."

Ms Wilkinson said supply was cut off to the public while extensive testing was carried out.

Contaminated gas was then pumped out and replaced. Most service stations affected are again supplying LPG.

Both BP and Shell have advised that if a service station is now selling gas, customers can be certain the LPG is safe to use.

"There was a contamination issue with fuel supplied to us (by Shell)," media manager for BP Chandran Vigneswaran said.

"Anyone experiencing an issue with their vehicle after purchasing fuel from us is covered by the BP fuels guarantee.

"That will cover the cost of related damage and any extra costs."

Ms Wilkinson said Shell was also willing to negotiate paying damage costs to its customers.

"We will consider all legitimate claims," she said.

Contaminated gas was sold from service stations in Melbourne’s northern and western suburbs as well as some in Bendigo, Ballarat and Warrnambool.

It is unknown exactly how many motorists have been affected and how much contaminated gas was produced.

Graeme McPherson in Golden Square said drivers who relied solely on gas had been most affected.

"People who have got dedicated gas vehicles can’t start them," he said.

Mr McPherson said he had received 15 phone calls from customers affected by the contaminated gas.