Oil prices retreated on technical trading Friday, ending a rally that had built through the week as refinery problems stirred worries about the ability to meet seasonal demand.

Light sweet crude oil for delivery in May settled at $19.67 per barrel, down 10 cents at the New York Mercantile Exchange."We lost a bit of the upside momentum of the last few days," said Roger Volz, analyst at Pegasus Econometric Group in New York. "Some traders were taking some profits."

Heating oil prices continued to move upward, though not as sharply, because of a burst of cold weather in the Northeast and Midwest. Analysts look for demand to slow next week, however, because extended weather forecasts showed a return to warmer temperatures.