Small Engines (Lawn Mowers, etc.): Trying to get lawnmower going!, caster oil, few more seasons

Question
I have a Craftsman 3.8 hp 22 inch lawnmower that was given to me for free. Model number 917-386073.  It could be at least 10 years old.  It worked last season, but won't start this spring.  I put new fuel in and changed the oil. (by the way, what's the best oil for this machine?) What can I do to see if I should junk it or if I can I hope to get a few more seasons out of it without putting too much into it.

Answer
You are always going to have to put something into it or it won't run.  I recommend a little liquid on our planet called "GAS."  Does it start?  Then throw it away is my motto.  Caster Oil is what all the pros use.  Good for the soul, good for your ohl.

Cletus