Fix on the way for Mazda CX-5 diesel

Mazda Australia expects within "a couple of weeks" to have a solution for the engine oil 'overfilling' problem experienced by some CX-5 diesel owners.

The issue, according to Mazda Australia's National Marketing Manager, Alastair Doak, applies to vehicles that regularly run short distances – down to the shops and back – without reaching normal operating temperatures.

Mr Doak told motoring.com.au that he has notched up 15,000km of open-road driving in a diesel CX-5 and hasn't encountered the problem during that time.

According to the Mazda spokesman, no more than "a couple of hundred vehicles" have been affected and the company will be in touch to let CX-5 owners know how Mazda will resolve the problem.

Apparently the diesel particulate filter that traps soot emitted during the combustion process needs the engine to build up enough heat to burn off the soot in the filter, but during regular trips of shorter duration the engine doesn't build up the required heat.

To stop the filter clogging with soot, diesel fuel is discharged during the exhaust stroke to raise heat levels faster, but some fuel finds its way into the sump, where it combines with the oil and increases the level in the engine.

Owners are concerned that engine damage may occur if this continues unabated, which is why Mazda has recommended owners check oil levels every 1000km. Mr Doak says that the new Mazda6 diesel is not susceptible to this problem.

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