Gas price drop from tapping oil reserves could be weeks away

NEW YORK (CNNMoney) -- Boosting the nation's oil supply could lower gas prices as much as 50 cents a gallon, but relief at the pump is still weeks away.

News that the Department of Energy will tap 30 million barrels of oil from its Strategic Petroleum Reserve to alleviate Libyan supply disruptions sent oil prices sharply lower Thursday. Many consumers hope that means gas prices -- now averaging well above $3.50 a gallon -- will quickly decline.

But crude oil is already down about 20% since peaking at $113.93 on April 29. Gas prices, however, are only off 9% from a high of $3.985 in March.

"It doesn't necessarily mean we'll see a ripple effect at the pump right away," noted Phil Streible, senior market strategist with futures broker Lind-Waldock.

Lower oil prices generally indicate that gas prices will fall too, although it may be weeks before consumers actually pay less at the pump.

It takes about 30 days to refine one barrel of crude oil into about 30 gallons of gasoline, said Robert Sinclair Jr., a spokesman for auto club AAA NY. That means it takes about a month for an oil price decline to translate into cheaper gas.

Any effect on gas prices will be further diluted by the fact that there already is plenty of oil on hand, added Michael Fox, executive director of the Gasoline & Automotive Service Dealer's of America, an industry trade group.

The oil stockpile already is above levels from last year, according to the most recent figures from the Department of Energy. "Oil is not the problem," Fox said.

Meanwhile, gas station owners and distributors will protect their profitability as long as possible, Sinclair said. When crude prices rise, gas prices quickly follow suit, but when crude falls, it takes a while before gas prices reflect the change. "That's just capitalism," he explained.

Dan Dicker, author of "Oil's Endless Bid: Taming the Unreliable Price of Oil to Secure Our Economy," predicts that the decision to tap oil reserves will ultimately result in a 50-cent drop in gas prices by the end of the summer.

That would be a boon for consumers. Although gas prices have inched lower in recent weeks, such high prices have put a burden on many Americans' budgets.

Gas spending and prices by state

The average price for a gallon of regular gasoline is $3.612, according to a daily survey by motorist group AAA -- about a dollar more than it was at this time last year.

Nationwide, drivers spent $392.57 on gasoline last month, which was 9.5% of the median income, according to the Oil Price Information Service. At its peak three years ago, gas accounted for 10.2% of consumer's income.