Diesel and crude oil made gains over the past week while gasoline prices dipped slightly, according to the Department of Energy's weekly on-highway retail price survey.

Gas dropped 1.4 cents to $3.462. That follows a nearly 6-cent gain last week. Monday's diesel price of $3.825, up 2.4 cents from last week, is as high as it has been in the past five weeks. One year ago, diesel was 75.8 cents per gallon lower than this week's price.

Prices were up across the country this week. California, up 4.3 cents to $4.096 per gallon, remains the most expensive region, while the Gulf Coast, which rose 1.9 cents to $3.745, reported the lowest price.

Meanwhile, crude oil gained some ground on Monday, rising $3.87 per barrel, or 4.4%, to close in New York at $91.27 -- the highest level in more than two months.

After bracing for a possible recession in the U.S. and Europe, analysts say investors have changed course. They're now trading with the expectation that Western economies will keep growing this year -- albeit slowly.