Oil prices slipped below $81 a barrel Monday as weak European stock markets dampened sentiment, the Associated Press reported. Benchmark oil for November delivery was down 62 cents to $80.96 a barrel at late afternoon Kuala Lumpur time in electronic trading on the New York Mercantile Exchange. The contract gained $1.61 to settle at $81.58 on Friday, the first time it topped $80 a barrel since early August. Oil held most of Friday's gains in Asian trading but weakened as European stock markets slid. Oil traders often look to stock markets as an indicator of investor optimism about the economy. In other Nymex trading in November contracts, heating oil was down 1 cent at $2.28 a gallon and gasoline fell 1 cent to $2.08 a gallon. Natural gas fell 4 cents to $3.76 per 1,000 cubic feet. In London, Brent crude fell 69 cents to $83.06 a barrel on the ICE Futures exchange.