Oil prices inched down from a five-week high on Thursday after surging 5 percent on growing worries that U.S. refiners' focus on meeting summer gasoline demand could worsen a winter supply crunch. Dealers have shrugged off the U.S. dollar's meteoric rise versus the euro this week and signs that OPEC would keep its taps wide open, pushing oil prices to their highest since late April and putting them only $4 below the April 4 record peak. U.S. crude oil futures shed 18 cents to $54.42 a barrel in early Asian trading, barely making a dent in Wednesday's $2.63 gain, the biggest one-day rise since Feb. 22. Prices are up 16 percent over the past two weeks. Heating oil led the market on Wednesday, gaining 6 percent to $1.54 a gallon, more than 50 percent higher than this time last year. Prices were down 5 points at $1.5395 on Thursday. With healthy gasoline inventories looking likely to last the summer driving season, which began at the weekend, dealers have shifted their attention unusually early to winter fuel supplies. "Obviously there's concern that there might not be enough diesel," said Colin Tang, an oil trader at investment bank Calyon in Singapore. As refineries typically produce more gasoline and less of other fuels in the spring, some worry that the industry may be ill prepared to meet peak heating demand this winter. U.S. commercial stockpiles of distillates, which include heating oil and diesel, are just 1 percent higher than a year ago, while demand is expanding at 3 percent over last year, government data showed last week.