“We are now sending out a letter to approximately 150,000 customers all over Europe, in approximately 30 markets, telling them that we are investigating a technical issue relating to increased oil levels in diesel engines with particle filters,” Volvo cars spokesman Per-Åke Fröberg told AFP.

Fröberg told AFP the company would consider a recall if its investigation showed that such action was necessary.

But he added that for the time being Volvo was “informing (customers) of the problem and asking them to check out their oil levels, which everybody should do anyway.”

“The problem is that engine oil may enter the combustion chamber and act as additional fuel. This leads to maintained or increased engine speed,” Fröberg

explained.

He said the problem could manifest itself in different ways, “but it could be that you take your foot off the accelerator and the car keeps the same pace as before or it might, in some isolated cases, also increase the speed.”

The problem was discovered after several incidents were reported by different customers in late 2009 and concerns eight car models that have a five cylinder diesel engine with a diesel particle filter.

Fröberg said the first notification letters would land in customer post boxes by the end of this week.

Those who see their oil level above the maximum indication should consult their Volvo dealer, he said.

In an interview with Swedish public radio, Fröberg said the problem could not be compared to the accelerator and brake defects that has caused auto giant Toyota to recall more than 10 million vehicles worldwide.

“First and foremost it’s not the same problem that Toyota has had. The biggest difference is that customers have the possibility of making sure it doesn’t happen by checking their oil level,” he said.

Swedish-made Volvo spent a little more than 10 years as a Ford brand before being sold in March to China’s Geely.