We recently purchased a 616 cut -n-fry, and we were wondering if you can use oil instead of shortening, and if not, why?  We want to get a good idea about how it works before we try it out.

Oil will not damage your 616.  Shortening is the preferred medium for preparing your donuts for a few reasons:    

     1.  Your donuts will not absorb as much shortening as oil while frying.

     2.  If you are preparing donuts that will be sitting in a case or otherwise for any extended period of time, gravity will affect the oil cooked donuts more.  The donuts will become "greasy" and/or "soggy" on the bottom with shelf time.  If you are doing a fast turnover (with little to no shelf time) this will not be an issue.