By The Associated PressPlatinum and palladium climbed Tuesday as traders expected that demand for the metals will stay steady as supplies drop. March palladium rose $7.65, or 1 percent, to settle at $765.45 per ounce. April platinum gained $9.10 to $1,707.20 per ounce. Reports of stronger car sales have helped pushed prices for the metals up more than 1 percent this week. Both metals are used to make catalytic converters that filter car exhaust. Prices of the metals tend to rise and fall along with car sales, said Erica Rannestad, a commodity analyst at CPM Group in New York. That's mainly because "there are no reliable substitutes" for their use in catalytic converters, she said. Other metals were mixed. Gold for April delivery lost $2.90 to $1,673.50 per ounce. Silver for March delivery rose 15.9 cents to $31.875 per ounce. March copper was barely changed at $3.77 per pound. In other trading, wheat and corn dropped slightly while soybeans rose. Wheat fell 5.5 cents to $7.575 per bushel. Corn slipped 5.25 cents to $7.29 per bushel. Soybeans edged up 6.75 cents to $14.955 per bushel. A report showing rising activity in the manufacturing and services sectors in Europe helped support oil prices. Benchmark oil for March delivery rose 47 cents to finish at $96.64 a barrel. In other energy futures trading on the Nymex: â¿¿ Wholesale gasoline added 3 cents to finish at $3.04 per gallon. â¿¿ Natural gas rose 8 cents to end at $3.40 per 1,000 cubic feet. â¿¿ Heating oil gained 4 cents to finish at $3.19 a gallon.