I have used Royal Purple of the correct weight, and either a K&N or a Royal Purple filter ever since the 5000 mile mark on my '10 CX9. The engine always ran smoothly, but with the synthetic, I don't get any "cold engine clatter." I change my own oil, and I habitually run it to the 7500 mile mark (per my owners manual) because I am not in a dusty environment, and my driving is about 75% freeway speeds. In Texas that means anywhere from 60 - 85. (We have a brand new 85MPH tollway from east of San Antonio to Austin.) Were I caught in stop and go traffic in my normal course of driving, I would consider that severe service, and drop the oil at 3000 mile intervals - and in that case would not use a synthetic.