The federal government is cracking down on phonies in the automobile repair business - not the grease monkeys who pretend they know something but really don't, but the replacement parts mechanics put in your car.

Automakers have complained that the bogus parts not only rob them of about $3 billion a year but could cause severe accidents.Federal officials have said some of the fake parts they've discovered include some high-volume ones such as oil filters, brake pads and shoes and antifreeze.

The danger, they say, is that because repairs or maintenance involving these parts is so routine, a consumer may not check to be sure that the parts are exactly what should be going on or into the car.

During the past year, the FBI staged a 15-state raid on dozens of businesses, looking for counterfeit General Motors Corp. parts.

Some of the parts that have showed up in the past included oil filters with rags jammed into perforated food cans and brake linings made of compressed wood chips and cardboard.

To combat the problem, GM has been testing the use of holograms on packages of its genuine parts. A consumer sees a mirrorlike square on the outside of the box that shows a multicolor GM logo when turned slightly.

Making and marketing counterfeit parts is a federal offense through trademark infringement.

New York attorney Milton Springut said there are four basic ways trademarks are violated:

- Repair shops say they are authorized by or associated with an auto manufacturer.

- Used-car dealers portray themselves as authorized dealers for a particular manufacturer.

- Parts are sold in packages containing counterfeit or look-alike trademarks of the automakers.

- Unlicensed parts are sold with the manufacturer's trademark.

There is nothing wrong with making or selling a replacement part for a particular vehicle as long as that part doesn't pretend to be from the original manufacturer.