Traders kept a wary eye on the Gulf of Mexico and the onrushing Tropical Storm Gustav, headed into the heart of gulf offshore oil installations. Evacuation plans were being readied.

The National Hurricane Center forecasts Gustav will likely reach the Gulf Coast early Tuesday. At that point, forecasters believe the gulf's warm waters will help the storm intensify as it heads toward landfall in the United States.

Natural gas also finished about even, dropping 0.02 at $8.02 per million British thermal units.

Heating oil was down .26 cents to 3.206 cents a gallon and reformulated gas was down .25 cents to 3.034 cents a gallon.

At the pump, U.S. motorists were paying an average of $3.669 for a gallon of regular gasoline, an increase over Thursday's $3.660, the AAA said.