Gasoline headed for the biggest weekly gain since December as supplies fell amid a seasonal switch to summer-grade fuel, which is more expensive to produce. Prices climbed as much as 0.5 percent. Gasoline supplies fell 1.6 million barrels last week to 229 million, the lowest level in eight weeks, according to Energy Information Administration data. PADD 1 supplies sank 2.8 percent to 59.5 million. “Refiners have to get rid of winter-grade gasoline and start to build up summer-grade gasoline,” said Dominick Chirichella, senior partner at the Energy Management Institute in New York . April-delivery gasoline rose 1 cent to $2.9555 a gallon at 10:08 a.m. on the New York Mercantile Exchange . Volume was 11 percent below the 100-day average. Prices are up 5.9 percent this week, the most since the period ended Dec. 20. The average U.S. pump price rose 1 cent to $3.484 a gallon, according to […]