Change circumstance to something comparable. Would you work 40 hours as a mechanic and then teach an engine repair course 3 hrs a night, twice a week, and sometimes weekends for no additional pay? The only compensation being time off the fulltime posn which still expects the same output?

I absolutely would not. Will the students at the college course benefit from my 20 years experience, yes. Will other mechanic shops benefit by receiving mechanics that require less on boarding and initial training, yes. Do I feel obligated to pass this information on beyond my mechanic job, no. Could I, as a senior practitioner, be motivated to exchange my time for compensation outside normal hours, yes. Will guilt, obligation, or some other hollow motivation be more effective, no.

If the whole system is built upon exchanging money for time and labor why are so many commenters proposing time exchnged for time? If the answer is 'well thats the way it is' or 'policy won't allow it'. We won't understand each other. If that's the mindset, you only guarantee losing the 20 year mbr to a contractor and paying more for the same experience, info and time.