I have a buddy who is/was a mechanic and have known him since he started his career in the auto world. He went through a 2 year program at the local community college, was an apprentice for about a year, then full time for after a year or so at a Chevy dealer. He was a mechanic for 5 years, with 3 different dealerships in those 5 years. He ended up moving from oil changes, to transmissions, to full auto work, whatever that's called.
He got bored, moved into a service adviser position and did that for 6 years. I don't know how he lasted, he was treated like shit, went through 3 dealers. Hours were stupid, 6a-6p, no lunch/breaks because he was always busy. Pay was fucked with every 3-6 months. Some time they would be straight hourly, sometimes salary, sometimes 40 + bonus depending on how much extra they sold, or service reports that were written up. They always worked 50-60 hours a week m-sat too.
I honestly never saw the upside. He moved into heavy machinery as a mechanic a few weeks ago after not being a mechanic for 6ish years, and they started him off at $23 an hour, he's up to $28 now and its been about a year, so it must be going well. His hours still suck, 9a-6p is his normal schedule m-f, and he's oncall because its for Pepsi CO and they deliver around the clock and he is the only mechanic in this territory.