Australian oil refiners faced total capital expenditure costs of hundreds of millions of dollars to upgrade their plants to produce lower sulphur diesel fuel, company spokesmen said late last week. Mobil Oil Australia Ltd corporate affairs manager Alan Bailey said reducing Australian sulphur content to current European levels of 500 parts per million would require major investment. "It is hard to put a number on it, but you are probably looking at investments to get a substantial reduction in the A$100 million range," he told Reuters. "The returns you are getting on refineries at the moment are pretty low and the concern we would have is, if we have to spend A$100 million, how do we get a return on that?"