I've finally switched to synthetic oil in preparation for the winter. Vehicle has about 66,000 miles. 5w30 was in the vehicle before, and replaced with the same grade but with synthetic this time. When accelerating the engine is noticeably louder than it was prior to the oil change. The oil level is good. When I'm at highway speeds and when the vehicle is idling, the engine sounds normal. In addition, when the car is in neutral and I step on the gas I do not hear the loud noise; it only occurs when the vehicle is in drive. Is this the nature of the thinner synthetic oil? Thanks.