2003 Ford V6, new in October. I don't know what the factory fill was, but I assume it was the now-recommended 5W-20 Motorcraft synthetic blend. I changed the oil (and filter) and refilled with that oil at 500 and 1000 miles. Now have 2300. I'm shopping for opinions on this issue as I cannot find any hard and fast data. Several Ford techs/service advisors have provided different takes on the occasions that I've asked them. I'm aware of the consensus that seating rings shouldn't be done on full synthetic. The 2300 miles on the engine in question is about 1500 city/800 highway. So, what do you think? When the 3000-mile change interval is up at 4000, am I good to go? Regards.