J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Favorite motor oil?

I have the older 2QM15. First time I changed the oil I used 10W 30 and it suddenly became hard to start on cold days. Got a lecture from my mechanical engineer dad about reading manuals and did so. I believe it calls for 5W. I used Mobile 1. Starts much easier. ("Started" I suppose since I haven't turned the key in almost 4 years.)