Use dino based oil like Lawn-boy or Legend oil. I always mixed new blocks at 32:1/30:1. Start and run part throttle for 5 minutes. Let completely cool. Start run 10 minutes part throttle. let completely cool. Start run 10-15 minutes full throttle no load. Let completely cool. Then run under load 10-20 minutes. Let completely cool. I was always able to get VERY NICE compression umbers with this system. Then move to 32;1 dino oil for first season. Only use synthetics after a complete season.I just bought a new OEM shortblock for a Lawn-Boy DF commercial engingine. Any tips on breaking it in properly would be greatly appreciated.