Tonight, a snake oil alert. Have you heard of the additive you can add to your car and magically add years to the cars engine. As we found out, don't believe what you hear.

Sound familiar? Calls bombarding you with an offer of an extended car warranty. Many find out the hard way that they bought into a service contract covering only limited repairs, not a warranty from a car manufacturer.

Dan Taylor, US Postal Inspector said, That is when they figured out, 'Hey this isn't what I thought it was.' At that point many victims had difficult canceling or even getting the refunds owed to them."

This un-ethical practice became so rampant states (like Missouri and California) started taking action.

"Various states put restrictions on them and even prohibited some companies from selling in those states," said Taylor.

To get around these restriction, creative companies turned to the so-called additive warranty. Small bottles of coolant or lubricants that come with the promise to "magically" protect your car.

"This additive was valued at several thousand dollars and as an added bonus an auto warranty was included with the package," said Taylor.

Pour the product into your car engine-consumers were told -and it will activate the auto warranty. It was a trap. Companies encouraged car owners to use the fluid, knowing it would nullify their chances for a refund.

"If they added the additive to their car they were told they could no longer get a refund because they couldn't return the additive or on the flip side if they didn't add the additive to their car the warranty was not valid," said Taylor.

How can you protect yourself:
1. Beware of any claims that an addititive is worth thousands of dollars.
2. If an auto warranty is included in the pitch, just hang up.
3. Always ask for a refund policy in writing.

If you're looking for an extended auto warranty, call your car manufacturer; don't buy additives or a warranty over the phone.