Oil prices are lower ahead of a weekend meeting where leaders of the world's biggest economies will look for ways to help Europe resolve its debt crisis.

Benchmark oil fell 60 cents to $91.96 per barrel on Friday in New York. Brent crude dropped 32 cents to $107.14 in London.

President Obama will convene the session of G8 leaders outside Washington. Concerns persist about Europe's financial problems and the impact they may have on the global economy. A big question is whether political turmoil in Greece could force it out of the group of countries that use the euro.

Meanwhile, AAA says the national average for retail gas prices fell about a penny to $3.71 per gallon. That's around 21 cents less than a year ago.