Like the others, I can only give you my experience. I have had: 2 OS. 46FX's, 2 OS 61FX's, 1 OS 91 Surpass, and a Saito 72. I have had to replace 1 61FX, and repair the Saito, but only because I was the one that put my dumb thumbs to the test and failed. Every engine that I have had so far has run right out of the box. However, I have had to send a radio back twice for repair, but for engines I am battng a thousand.