By Steve Gelsi

Energy stocks made more gains Friday, the final trading day of a robust May, as shares of petroleum producers and refiners tapped into the highest crude-oil prices seen in six months.

Oil's big rise in the commodities futures pits, along with a traditional bump up in the energy business ahead of the summer driving season, helped shares of petroleum and natural-gas producers ride the rally in the broad market in recent weeks.

Friday proved no exception, as oil broke through the $66-a-barrel level, even while the broad equities market wavered following Thursday's solid gains.

Against this backdrop, the Amex Oil Index (XOI) rose 1.3% to 982.

The Philadelphia Oil Service Index (OSXX) gained 1% to 175, while the Amex Natural Gas Index (XNG) added 0.6% to 437.

Shares of sector leader Exxon Mobil (XOM) climbed 53 cents to $69.76 as Chevron (CVX) rose $1.02% to $66.83. Both oil majors are components of the Dow Jones Industrial Average (DJI).

Meanwhile, average U.S. retail gasoline prices rose to $2.47 a gallon at the end of May, up from $2.05 a month ago - good enough for a quick jump of 20% in the past 30 days.

With one trading day left in May, the Amex Oil Index has climbed to 970, up from 876 on April 30, for a gain of 10.7%.

The Amex Natural Gas Index now sits at 434, up from 387 on April 30, for a gain of 12%.

And the Philadelphia Oil Service Index (OSXX) closed out trading on Thursday at 173, up fully 14.6% from April 30.

Among other energy stocks in the spotlight, First Solar (FSLR) rose 3.8% to $11.16. The largest U.S.-based maker of panels for solar energy was mentioned in a Goldman Sachs note this week as one of five potential contenders to replace General Motors (GM) in the S&P 500.

-Steve Gelsi; 415-439-6400; AskNewswires@dowjones.com

Order free Annual Report for Exxon Mobil Corporation

Visit http://djnweurope.ar.wilink.com/?ticker=US30231G1022 or call +44 (0)208 391 6028