Dollar General, Dollar Tree, and Family Dollar will pay New York State over $1 million after an investigation turns up illegal practices.

The New York Attorney General's office revealed the results of a multi-month investigation into three dollar store chains. Undercover shoppers found products for sale that could be dangerous for humans, as well as their automobiles.

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The first part of the investigation uncovered out-of-date medications and drugs for sale on shelves at a number of the local dollar store chains. It's illegal in New York State to offer over-the-counter medication that is past its expiration.

Another investigation found Dollar General was selling its own brand of motor oil that is not suitable for most cars. Shelves were stocked with DG SAE-30 oil, which is not made for most car engines that were built after 1930. In addition, there was also DG SAE 10W-40 and DG SAE 10W-30 motor oils for sale which should not be used on most engines built after 1988. What's more, the motor oils were in packages marketed to look like modern motor oil and placed next to the newer oil on shelves. There were no warning signs posted that the oil is not intended for modern cars.

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More investigations revealed both Dollar Tree and Family Dollar stores in New York were in violation of bottle deposit laws. Some stores would not accept returns, as mandated by the state. Other stores were charging a deposit on bottles that are not subject to a deposit, like Starbucks Frappuccino drinks.

Dollar General has since discontinued the sale of obsolete motor oil and agreed to pay $1,100,000 to the State of New York. Dollar Tree and Family Dollar will pay $100,000 for not following the bottle deposit laws and promise to retrain their employees. As for the expired medications, several new procedures are now in place to make sure out-of-date drugs no longer make it to store shelves.

If you believe you purchased obsolete motor oil from Dollar General, you can submit a complaint form and request a portion of the penalties paid to the New York Attorney General reserved to compensate customers affected by the illegal sales.