SAN FRANCISCO (KGO) --California gas prices have dropped 31 cents in the past month. Over the weekend, they could go up by that much.
Californians have been getting a break at the pump.
"Lowest I've seen in years. I hope it don't go back up," said Al Wong, a driver.
It's become a tradition, as oil refinery switch from the winter blend to the state-mandated summer blend meant to reduce smog.
It has Southern California-based Consumer Watchdog howling. They say this weekend, the wholesale price of brand name gasoline is going up 37 cents a gallon, most of it likely passed on to drivers.
"We call it the golden state gouge. There are four companies raising prices at exactly the same time for no good reason and making a ton of money," said Consumer Watchdog president Jamie Court. "So buy your gas today, because gas prices are only going to go up. They're not going to come down. And they're going to go up like a rocket, and it's not even likely they're going to come down like a feather. They're just going stay high for a while."
Try explaining that to consumers.
"The oil comes out of the same hole. The same people are pumping it," said one San Francisco customer.
Consumer Watchdog doesn't understand it either.
"Whenever there's a blend the refineries pretend like they didn't' see it coming, and then suddenly there's a shortage, so what you're seeing right now is them saying, 'Oh look we don't have enough summer blend gasoline, so there's suddenly a price spike," said Cody Rosenfield, a Consumer Watchdog researcher.
They're accusing refineries of working together to fix prices.
"We think that there are signals, that each refinery sends to the other that arise to the level of what's called a tacit agreement. If you can prove a tacit agreement, they've committed a crime," Court said.
The Western States Petroleum Association that represents the major refineries says it's not price fixing, it's just business in California's complex oil market.
"Know how they are. They're there to make money, not friends," said another gas station customer in San Francisco.