I'm finding that I will put 3-4 hours on it then go a week without using it. She certainly gets up to temp in that time.   In about 2 weeks time I will be done my spring work and she will sit for a few months.  Then I will have a bunch of work in the fall for it.  I don't mind using synthetics on the engine. It's cheap. 
  The hydro, I may just use Donax Td.  It's easy to get around here and 1/3rd the cost of synthetic.  Correct me of I am wrong but the hydro oil wouldn't see the temps that the engine would.  Is that a good assumption?