There is a ton of oil in it, and there is definitely some rust, does it look bad?
I picked this motor up on ebay used, it looks new on the outside, the piston looks new, you can tell the motor has never been mounted on a plane, only a test stand.
I'm thinking it's seen maybe 10 ounces of fuel on a stand then got thrown on a shelf for the last couple years.
This is a OS 91fx