Oil prices are falling once again, and relief at the gas pump is likely on the way too.

But be careful what you wish for. Low gas prices can sometimes be more a symptom of a weakening economy, than a cure to consumers’ woes.

Crude oil briefly dipped below $80 a barrel on Friday, about 30% below its peak at $113.90 in April.

Meanwhile, gasoline prices — which often fall one to two weeks after oil — were at a national average of $3.59 a gallon Friday. Gas is likely to decline to around $3.50 a gallon in the next week, estimates Chris Lafakis, economist with Moody’s Economy.com.

That could be a good thing, he said. After all, lower gas prices give Americans more money in their wallets. At a time when sluggish consumer spending has been one of the biggest drags on the U.S. economy, that’s a welcome change.

The rule of thumb is that for every $1 decline in the price of oil, American consumers have an extra $3 billion to save, spend or pay down their debt over the course of an entire year.

In this case, if oil was to stay around the $80-a-barrel level for a year, that could essentially amount to a $90-billion-stimulus for consumers, Lafakis said.

But that’s not the entire story. Remember the 2008 recession? Gas prices fell then too, and it still wasn’t enough to bail out the American consumer.

“There’s a fine line here. When falling prices cross the line into deflationary prices and economic activity freezes up, that becomes a real problem,” said Phil Flynn, senior market analyst with PFG Best.

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