Oil prices fell for a second day on Monday on fears of lower fuel demand from an expected global recession sparked by rising worldwide interest rates and as a surging U.S. dollar limits the ability of non-dollar consumers to purchase crude.

Brent crude futures for November settlement slipped 54 cents, or 0.63 percent, to $85.61 a barrel at 0511 GMT. Meanwhile, U.S. West Texas Intermediate (WTI) crude futures for November delivery dropped 48 cents, or 0.61 percent, to $78.26.

Both contracts slumped around 5 percent on Friday to their lowest since January.

The dollar index that measures the greenback against a basket of major currencies climbed to a 20-year high on Monday.

A stronger greenback tends to curtail demand for dollar-denominated oil since buyers using other currencies must spend more to buy crude.

Central banks in numerous oil-consuming countries, including the U.S., the world's biggest crude user, have raised interest rates to fight surging inflation which has led to concerns the tightening could trigger an economic slowdown.

"A backdrop of global monetary policy tightening by the key central banks to quell elevated inflation, and a splendid run-up in the greenback towards more than two-decade highs has raised concerns about an economic slowdown and is acting as a key headwind for crude prices," said Sugandha Sachdeva, vice president of commodity research at Religare Broking.

Sachdeva expects WTI prices to find a floor at $75 a barrel, while $80 will serve as a cushion for Brent.

Attention is turning to what the Organization of the Petroleum Exporting Countries (OPEC) and allies led by Russia, together called OPEC+, may do when they meet on October 5, after agreeing to cut output modestly at their last meeting.

But, since OPEC+ is producing well below its targeted output, any announced cut may not have much impact on supply.

Data last week showed OPEC+ missed its target by 3.58 million barrels per day in August, a larger shortfall than in July. 

(Source: Reuters with edits)