I change the oil on my 2008 5.4L V8 every 5,000 - 6,000 miles, with Mobil 1 High Mileage Synthetic 5W20, and with a Motorcraft filter. Oil is usually pretty dark at that point, and it only costs me about $40 for the oil and filter at Walmart. It only takes about 30 minutes and I consider it to...