Brent North Sea crude for September added 70 cents to 81.52 dollars in late morning London deals.
Oil had surged past 81 dollars on Monday, with sentiment boosted by soaring global stock markets, strong bank results and solid US economic data.
Further support came from the weak greenback, which makes dollar-priced commodities cheaper for buyers using stronger currencies, and therefore tends to stimulate demand.
"The combination of bullish stocks, a weak dollar and most notably the hurricane season has pushed the price of oil over 81 dollars a barrel," said analyst Rebecca Seabury at the Inenco energy consultancy in London.
"In the short term, the hurricane season is likely to continue spurring on bullish sentiment in the oil market, as potential storms threaten US and Mexican infrastructure.