Oil prices drifted above $81 a barrel Tuesday in Asia, the Associated Press reported. Benchmark crude for May delivery was down 12 cents to $81.48 a barrel at late afternoon Singapore time in electronic trading on the New York Mercantile Exchange. The contract added 63 cents to settle at $81.60 on Monday. The euro fell to $1.3510 on Tuesday from $1.3560 on Monday while the dollar rose to 90.25 yen from 90.10. In other Nymex trading in April contracts, heating oil fell 0.6 cent to $2.077 a gallon, and gasoline dropped 0.9 cent to $2.276 a gallon. Natural gas rose 1.5 cents to $4.094 per 1,000 cubic feet. In London, Brent crude was down 12 cents at $80.42 on the ICE futures exchange.