Crude oil prices slipped in Asia on Friday ahead of a speech by Fed Chair Janet Yellen expected to set the tone for markets.

On the New York Mercantile Exchange, West Texas Intermediate crude oil for delivery in October traded at $93.90 a barrel, down 0.07%, after hitting an overnight session low of $92.63 a barrel and a high of $94.44 a barrel.

Brent oil rose to $102.71 a barrel, up 0.42%, on Thursday.

The Federal Reserve Bank of Philadelphia said that its manufacturing index topped a three-year high of 28.0 this month from July’s 23.9 reading. Analysts had expected the index to decline to 19.2 in July.

Separately, market research group Markit said that its preliminary U.S. manufacturing purchasing managers’ index increased to a four-year high of 58.0 this month from a final reading of 55.8 in July. Analysts had expected the index to ease down to 55.7 in August.

Data also showed that U.S. existing home sales increased 2.4% to 5.15 million units last month from 5.03 million in June. Analysts had expected existing home sales to dip 0.4% to 5.02 million units in July.

Also on Thursday, the U.S. Department of Labor said the number of individuals filing for initial jobless benefits in the week ending Aug. 16 decreased by 14,000 to 298,000 from the previous week’s revised total of 312,000.

Analysts had expected jobless claims to fall by 12,000 to 300,000 last week.

U.S. data offset a disappointing factory gauge out of China, the world's second-largest consumer of crude oil.