Most of the time, job postings will tell you the number of years of experience that are required for the job. Maybe he's setting his sights too high, applying for jobs that require some experience. That's not a bad idea - maybe he'll find someone that really thinks his talents are a good fit and is willing to bend the rules (this is much more likely to happen in a small company than a larger company) - but it should not be his only strategy. Specifically look for entry level jobs.
It would be a good idea to visit the career resource department of his college. If a company is looking to hire an entry level employee, they're going to be looking at colleges. The career resource people will be able to keep him up to date on career fairs and companies coming to interview. They can also help him polish up his résumé and cover letters, and work on interview skills - that never hurts! And since he went to a technical school, they probably work with a lot of companies that are looking for mechanical engineers. If he's not still located somewhere nearby OIT, there's probably another school he's close to that could help him out. Might be a good idea to call someone at OIT's career resource department and ask them if they know anybody at a local school that can help him out. It's good practice for networking!
In the meantime, it's important to keep his skills fresh. He's probably working as a waiter or at a car wash or whatever, which helps pay the bills, but it doesn't make him any more attractive to someone who wants to hire an engineer. He should consider auditing some classes at OIT, or whatever school is nearby. Maybe some interesting electives that he didn't get a chance to take, or some upper level classes. Hell, take the GRE and try to get in a masters' program - that's what I did, when I didn't have any job offers after finishing my bachelors in 2002. Short of that, take up a hobby that offers real world experience. Help somebody rebuild an engine. Start a team to build a pumpkin catapult. Maybe there's a warbird museum that he could volunteer at.
Mostly, don't get discouraged. Almost any company you can think of needs mechanical engineers, and since he doesn't have any experience, he's not getting locked into one field or one industry. Boeing, Lockheed, Northrop Grumman, Pratt & Whitney, Cessna, United Launch Alliance, Orbital Sciences, SpaceX, and other aerospace companies. Otis Elevator. Anybody that builds boats or jet skis. Or snow skis and snow boards. Bridges and buildings are civil engineering, but a mechanical engineer would be able to pick it up easily. Cell phones and other electronic devices. Ford, GM, Toyota, Chrysler, and the rest of the auto industry, plus heavy equipment like Caterpillar. The people that make tennis rackets and golf clubs, or fishing line, or windows and doors. A friend of mine just got a job with Tony Stewart Racing. d**n near anything you can think of, a mechanical engineer either built it, or built the machines that built it.
Many of those companies advertise on websites like careerbuilder, but plenty of them hire through their own websites. So he should look for those.
And ***DON'T FORGET THE FEDERAL GOVERNMENT!*** NASA, the Federal Aviation Administration and the rest of the Department of Transportation, the US Patent Office, civilian military, they all hire mechanical engineers. As a matter of fact, if he hasn't gone to http://www.usajobs.gov
yet, he should do that TODAY. Look at state governments, too.
So, good luck to him! It's tough right now, the economy isn't great. But there are jobs to be found.