You should be using non detergent oil for like the 250 miles then conventional oil until about 1000-1500 miles and then synthetic if so desired after. If you have confirmed you have no leaks and you think the rings haven't seated yet then try this. Find a steep hill and at the base of the hill be in a higher gear and low rpm maybe 3rd gear at 2k then floor it and put a good load on the engine. Bring the rpms up to about 4500 and hold as you climb hill. The drive normal through town try not to stay in same rpm range. This method has always helped me seat rings.