Oil falls for a third session; natural gas gains

SAN FRANCISCO (MarketWatch) -- Crude-oil futures closed lower Friday for a third-straight session, pressured by concerns over Greece's debt crisis and weak U.S. gasoline demand as investors downplayed Iran's threat to global oil shipments. Oil for February delivery shed $1.93, or 1.9%, to settle at $98.46 a barrel on the New York Mercantile Exchange, with futures prices marking a loss of 0.2