I'm a MechE working in petrochemicals since 2012. Business card says 'maintenance', but heavily involved with projects as well.
A year or so after graduation, I decided getting a Master's degree would be a brilliant idea. After all, the company was going to pay for it! I absolutely loathed school for my entire 5 year undergrad program, but it seemed like the right thing to do.
Failed both of my classes first semester. Had absolutely zero motivation to do anything school related. Burnt $7,000 in tuition + books.
Found a new job half way across the country. Decent pay bump, living near the 'Petro Metro' of the US, plus no more brutally cold and snow filled winters. New job kind of sucked right off the bat, though.
Four years later I'm making 75% more money while doing the same type of job I was doing before my failed attempt at "grad school". New job isn't so new anymore. Still kind of sucks. But it pays decently and I've learned quite a bit.
I absolutely love turbomachinery, and the only redeeming quality about my job is that I get to deal with compressors and turbines on a semi-regular basis. I want to stay in a plant environment, which kind of pigeonholes me into a super niche field when it comes to looking for a job.
But even branching out and looking at other turbomachinery related jobs, I've never seen a Masters degree REQUIRED. I really doubt it would have any significant impact on employment or long term salary/income. You could definitely work at an OEM or aftermarket repair shop with a BS degree, just need to get your foot in the door somehow. And again, I don't think an MS degree would shortcut you to employment there.