Exxon, Chevron results augur tough year ahead, shares drop 3.5%

HOUSTON (Reuters) - Weaker crude oil and gas prices drove quarterly results sharply lower at Exxon Mobil Corp and Chevron Corp, pushing down shares at the two largest U.S. oil producers and signalling a weak start to the new year. While one-time asset sales or write downs were large factors, the two companies said earnings suffered from weaker margins in crude oil, natural gas, chemicals and fuel production. They gave tepid outlooks for the near term."There's no silver bullet on improving..