NEW YORK — On-highway diesel prices fell by 6.4 cents in the U.S., an even larger drop than last week, according to a weekly report from the Department of Energy.

National average prices south of the border dipped below $4 per gallon (but just barely at $3.99) for the first time in several weeks.

Oil dropped sharply to below $100 a barrel early in May. The DOE says the lag between oil price fluctuations and prices at the pump is typically about two weeks.

Prices receded in Canada as well in the last week. The average price of a $1.25 a liter is about three cents lower than the week before of May 10.

Prices in northern Ontario, northern Quebec and the Maritimes was the highest, averaging over $1.30 in some cities.

Southern Alberta, as always, had the lowest prices – around $1.15 a liter.