Warrnambool service stations sold unleaded petrol for between $1.38 and $1.42 a litre yesterday while the average in Melbourne for the same product ranged between $1.21 and $1.25 a litre.

Petrol outlets in Portland, Hamilton and smaller Western District towns were charging as high as $1.50 a litre for unleaded this week, although experts suggest prices statewide are on a downward trend.

RACV fuel expert Michael Case encouraged south-west motorists to vote with their feet and be more strategic about fuel purchasing.

He said motorists heading to Geelong or Melbourne should fill up while in the state capital to “send a message” to south-west service stations.

“Petrol prices should be less than $1.30 a litre in Warrnambool, not more than $1.40 a litre,” Mr Case said yesterday.

“If you’re already in Melbourne on the weekend, fill up while you’re in the city and send a message to the service stations in south-west Victoria that prices are too high.”

Saudi Arabia and the United States have been locked in an oil output race since early November, shaking up international pricing mechanisms and having a knock-on effect to retail petrol prices.

This week unleaded prices in Warrnambool were at the lowest level since the near-miss recession in late 2008, when demand for oil plummeted internationally. 

In mid-2008, petrol sold for more than $1.60 a litre at south-west service stations but following the global economic downturn, unleaded was priced as low as $1.05 a litre by Christmas 2008.

Mr Case said the Melbourne petrol price cycle had been unpredictable during the past three months, with the cost of unleaded remaining low.

“For three consistent weeks, we’ve seen the price of unleaded in Melbourne stay at the low end of the cycle, which is unusual,” he said.

“The price has gradually fallen in Warrnambool, which is good considering some towns have seen little change, but it can afford to fall further.”

Colac-based fuel advocate Phil Edge said the south-west was regularly hit at the petrol pump by far higher prices than the metropolitan average.

“It’s less than an hour’s drive between Geelong and Colac, yet there’s consistently a 20 to 30 cent price gap per litre,” Mr Edge said.

“That’s not a new thing. We’ve been battling against that since the 1980s, probably even before that. 

“If Colac was 400km or 500km away from Melbourne, it would make sense, but even Warrnambool seems to beat us when it comes to petrol prices.”

The Australian Competition and Consumer Commission (ACCC) released a comprehensive petrol price report this week which showed the average retail price for unleaded was $1.50 cents per litre in the five state capitals during the 2013-14 financial year.