Try the Marvel first. I would recommend pouring in a qt,let it idle for about an hour then drain it and do your oil/filter change. I don't think loading the motor with MMO in there would be a good idea. Regular ol 10w40 high zinc oil would be my choice for your climate. I've only run synthetic in my Harleys for about a year and and quit when I didn't notice any benefit of that high priced crap. I've always run crude in my passenger vehicles and I drive them till the wheels go square.