By Claudia Assis
SAN FRANCISCO (MarketWatch) -- Crude-oil futures traded higher Tuesday, as a successful Spanish bond sale and data showing German investor confidence rising for the fifth month in a row buoyed commodity markets. Gold futures, however, wavered between small gains and losses after spending most of the early trading in the black. Gold for June delivery GCM2 -0.25% retreated 60 cents to $1,649 an ounce on the Comex division of the New York Mercantile Exchange. Oil for May delivery CLK2 +1.59% advanced $1.74, or 1.7%, to $104.63 a barrel on the Nymex.
