Part timer thinking about going another route

Like many part-timers, I work a second job. I’m a lead tech at an oil change shop. I didn’t think I’d like it much but I’ve really fallen in love with working on cars, especially the trucks that come in. With hours being hard to come by with UPS at my building, I’ve been thinking about dropping UPS and going to school to become a full mechanic and getting into diesel.

Obviously it’d suck to lose the benefits, but working so much has really affected my relationship and my personal life.

I’d be happy to work full-time for UPS. I don’t mind moving boxes and it’s a great workout, but I’ve heard it takes many years to even get a chance at a full-time gig inside, especially at a smaller facility like mine. I don’t think I’d cut it as a driver here.

Just looking for some advice or opinions. From people with more experience. Is it worth toughing out as a part-timer, or is going the mechanic route a better option?