The United Steelworkers union (USW) said a new contract offer was made by lead oil company negotiator Royal Dutch Shell Plc (RDSa.L) on Wednesday night as a strike by U.S. refinery workers ended its fourth day. About 4,000 workers at nine plants, including seven refineries accounting for 10 percent of U.S. refining capacity, continue to walk picket lines in California, Kentucky and Texas. A drop of more than 50 percent in oil prices since June has eroded profits at major oil companies, prompting executives to say they cannot afford to lift wages for workers.