UPDATED 08/21/12 – 7:31 p.m.

CHICAGO (CBS) – Thousands head across the state line to Northwest Indiana for a cheap fill-up, but now, BP is recalling two million gallons gallons of bad gasoline there.

And as CBS 2’s Susanna Song reports, you could be affected even if you didn’t fill up at BP.

LISTEN: WBBM Newsradio’s Steve Miller reports

BP initially said the product in question is regular unleaded gasoline that came from the Whiting facility between Monday, Aug. 13 and Friday, Aug. 17. It could have been sold at BP and other retail outlets in the Northwest Indiana region.

But later Tuesday afternoon, BP said premium and mid-grade fuel trucked to Milwaukee might also have been affected. That fuel was sold between 10 p.m. Monday and 6:45 a.m. Tuesday.

However, a BP spokesman said it appears the greater northwest Indiana area around Lake County “still appears to be the epicenter.”

LISTEN: WBBM Newsradio’s Bob Roberts reports

“The company believes that fuel stored in a tank at the storage depot could cause hard starting, stalling and other drive-ability issues,” BP said in a written statement Monday.

On Tuesday, phones were ringing nonstop at the Schepel Buick GMC in Merrillville, Ind., mainly because of customers complaining their cars suddenly won’t start, and have made strange sounds.

The customers may now need a costly fix, and bad BP gas is believed to be to blame.

Schepel Buick GMC service manager Bill Vliestra has had to help 150 customers over the phone.

“It’s been all over. We’ve had one customer yesterday who filled up Saturday or Sunday in New Buffalo, Michigan,” he said.

BP issued a recall on unleaded regular gas in Northwest Indiana, after about 25,000 gallons had reportedly been shipped. CBS 2’s camera was rolling when a BP representative came to pick up a sample of the fuel – the same fuel Vliestra showed us earlier.

The fuel had a film of contaminant floating on top.

The same liquid came from inside the tanks of several sport-utility vehicles being repaired, where the service engine light was on.

“It’s fixable,” Vliestra said, but it won’t come cheap. “That depends on how much, we have to drain the tank, and clean the injectors and fuel filters. You could spent 3, 4, 500 dollars.”

Antrice Murray is a regular customer at the Hammond BP, and noticed “a rattling sound, like you want it to stop,” when she gassed up on Wednesday.

“I’m taking off of work,” Murray said. “I’m taking my car to the shop to find out exactly what’s going on.”

For Margie Smith, she says not only is her engine light still on inside her Volkswagen Jetta, but her motor started to sputter after she gassed up last week.

“This morning when I got up to start it, it acted like it didn’t want to start, like, you know, maybe I needed a tune-up,” Smith said.

Smith he brought her car back to the dealer, Team Volkswagen in Merrillville, Ind., where Wes Griffith says he’s taken hundreds of complaints from people whose cars wouldn’t start.

“They also had concerns with … shaking when they were going down the road, ‘check engine’ lights flashing, things like that,” he tells CBS 2’s Pamela Jones.

Vliestra says the bad gas problems have affected drivers differently.

“It seems like the people that were half a tank or more and just topped their tank off have the condition, but not as severe as the ones that were maybe really empty, and put whole tank in,’ he said.

“We stand by our product, guarantee gallons. If a customer has fuel related problems that can be traced back to BP fuel, we will reimburse them.”

Griffith has a solution, although it will cost a little more.

“Right now, we believe the best thing is to run the fuel out, and switch to a premium fuel, instead of regular unleaded,” he said.

BP released a new statement Tuesday in response to the bad gas crisis.

“The company believes that fuel stored in a tank at the storage depot could cause hard starting, stalling and other drivability issues. The fuel may have been purchased by motorists patronizing BP and other retail outlets in Northwest Indiana during the past seven days,” BP spokesman Scott Dean says in the statement. “BP is committed to fuel quality and guarantees every gallon of gasoline we sell.”

And while BP gasoline is affected, it is not only BP stations that have received the contaminated product.

Some of the fuel was sold at stations that do not fly the BP flag but are supplied by its trucks, including Thornton and Costco, Dean said.

Meijer grocery store also reported calls about bad gas that had been sold its stores in Merrillville and Highland, Ind.

BP is advising that anyone who has encountered car trouble because of bad gas should hold onto their receipts, as the company needs a record of a credit or debit card purchase to provide a refund. Consumers are also advised to document any repairs made to their cars because of the bad fuel.

And any consumer who paid in cash for the gas is asked to get a mechanic to get a fuel sample from his or her car, so BP can verify where it came from.

BP has opened up a customer hotline if you have any questions or concerns. The number is (800) 333-3991.

However, wait times on that hotline were so bad that the petroleum giant has now assigned 90 operators to receiving complaints.

If you have trouble getting through on the hotline, you can also email BP at bpconsum@bp.com.