"This link is to a study comparing many manufacturers oil. It is long but very interesting for someone who really wants to know how their oil performs. I personally won't use a full synthetic in an engine until it has around 1000 miles on it because synthetics lubricate so well that rings and other mated parts might not seat right" I have heard this before also. That is why I have been using Yamalube until now. for still want to use a non synthetic oil for a couple hundred more miles but would like to find a good 10-40 oil not the Yamalube 10-30. With summer just about here the 10-30 only works up to about 70 degrees according to the manual. I am thinking of using Honda 10-40.