sorry for the lack of specifics. No SOP's to deal with the situation. We were flying a 19 seat turbo-prop with garrett engines in the canadian north. I was of the opinion that we should have kept the engine as long as the other parameters were ok (no indication on engine that there was a leak and we are not pressurized). The captain however, wanted to save the engine and not find that it "grinds to a halt" when we are short final or deciding to overshoot. Then, I thought it was too early to shutdown but in hind sight I think he was right. Sooner or later I will be forced to make the decision so I wanted advice from you guys/girls.