Oil prices edged lower on Friday, but were set for a second straight week of gains as optimism over a resilient US economy and falling interest rates pushed up hopes of improving demand.Brent oil futures expiring in October fell 0.2% to $80.88 a barrel, while West Texas Intermediate crude futures fell 0.3% to $77.93 a barrel.Brent was set to advance 1.6% on a weekly basis, while WTI was on track for gains of about 1.5%.Investors found renewed optimism around US economic growth after a string of data releases this week.On Thursday, a government report showed US retail sales rose 1% last month, well above market forecasts for a 0.3% gain. Also on Thursday, data showed that fewer Americans filed new applications for unemployment benefits last week.Source : Qatar News Agency