The national average price for a gallon of diesel fuel has dropped 6.6 cents over the past week, according to the Department of Energy.

This week's drop marks the lowest point in an eight-week slide that has taken diesel prices to their best level since October 24. Still, diesel remains nearly 60 cents higher than it was a year ago.

As usual, west coast diesel prices were the highest in the country, averaging a dime higher than the national average. Prices on the Gulf Coast hovered about a dime below the national average. California is still above four dollars at $4.047 per gallon.

Gasoline prices continue to drop, falling another 5.7 cents this week to $3.229 a gallon. It was the fifth straight drop.

Oil prices rose slightly Monday following a 7% drop last week. Benchmark crude gained 35 cents to end at $93.88 per barrel in New York.

The volume of oil trading slowed on Monday with only two, holiday-shortened weeks left in the year. Many oil traders continue to sell their remaining investments for 2011 in an end-of-the-year purge that helped push oil prices lower last week.