Will probably run Motorcraft 5w30 synthetic year round or Mobil 1 0w/30 (winter) and Mobil 1 5w30 summer. I work at a Ford dealership, so I can purchase at cost plus 10%. Motorcraft is a little more readily available. Either will cost me a little more than Wal-mart prices, but I don't have to stockpile or worry about disposal. I have a stock of Wix filters that I will use up.