Crude oil prices climbed toward US$50 a barrel on Wednesday after a refinery glitch in the United States rekindled worries about gasoline supplies ahead of the start of the American summer driving season. Light, sweet crude for July delivery rose 5 cents to US$49.72 a barrel in electronic trading on the New York Mercantile Exchange at late afternoon in Asia. Heating oil prices fell marginally to US$1.3865 a gallon (3.8 liters) while unleaded gas fell to US$1.4225 a gallon. Reports Tuesday of a shutdown at Exxon Mobil's Baytown refinery in Texas sent crude prices upward. After the news, the benchmark commodity settled 51 cents higher at US$49.67 per barrel on Tuesday after rising as high as US$49.94 per barrel. The refinery glitch happened at a time when analysts were especially concerned over aging U.S. refineries and their output when production is ramped up to meet summer demand following this Memorial Day weekend, The Associated Press reported. The American Automobile Association predicted last week a record 36.9 million Americans will travel 80 kilometers (50 miles) or more this Memorial Day weekend, with nearly 85 percent leaving home by motor vehicle. Prices have fallen about US$9 since hitting an all-time high of US$58.28 on April 4.