Prices for fuel keep moving lower as oil costs are at some of their lowest levels in at least two years.

On Monday the U.S. Energy Department reported the sixth consecutive drop in the average price of on-highway diesel, down 4.2 cents from last week to $3.656. Factoring in weeks when the average diesel price was unchanged from the week before, diesel prices haven't increased since late June.

The current price compares to a high for the year of $4.021 hit on March 10 and is the lowest since July 2012. It's 23 cents less than same time a year ago.

Prices are down in all parts of the country over the past week, with the smallest decline happening in the Rocky Mountain region, 1.2 cents, for an average of $3.738. The biggest drop occurred in New England, down 6.4 cents for an average of $3.751 -- still the second most expensive part of the country.

Diesel ranges from a low of $3.589 in the Gulf Coast region, down 4.8 cents from last week, to a high of $3.835 in the West Coast region, a 5.6-cent drop during the same time. Compared to a year ago the regions are down at least 21 cents per gallon.

The average cost of regular grade gasoline posted an even bigger decline over the past week, falling 8.7 cents to $3.12 per gallon. Compared to this time last year the price is 24 cents less.

Regionally, prices are down by at least 5.6 cents over the past week and are at least 17.6 cents less compared to the same time last year.

Gasoline ranges from a low of $2.912 in the Gulf Coast region to a high of $3.424 in the West Coast region.

Meantime, the price of crude barely moved lower on Monday, but it is down more over the past week, after briefly going below the $80 per barrel level in trading last Thursday. It settled at $82.71 in New York, four cents lower on the day but down more than $2 from where it opened last Tuesday.

Last week U.S. oil lost 3.6% and is down for three consecutive weeks. Brent crude in London has fallen for four consecutive weeks, including losing nearly 5% last week. These are near two-year and four-year lows, respectively.

Analysts attribute the recent decline to increasing supplies of U.S. crude while worldwide demand is falling, due in part to less economic growth in some countries. So far, the OPEC oil cartel hasn’t signaled it’s poised to do anything about lower prices, with its next meeting not scheduled until the end of November.