Oil prices edged lower on Friday after the U.S. central bank warned on the health of the global economy and bearish signs persisted that the world’s biggest crude producers would keep pumping at high levels to maintain market share. The Federal Reserve decided against raising interest rates from historic lows on Thursday, saying uncertainty about global economic growth had forced its hand. “The perception of ‘ZIRP (Zero Interest Rate Policy) forever’ should provide some underlying support to the commodity complex,” said Olivier Jakob, a strategist at Petromatrix, a Swiss-based consultancy.