I would recommend that you switch to rotella 10W30, you can still get in the gallon jugs.. The local wal-mart has it in stock all year around.. Ford actually shipped the 7.3 psd in the superdutys with 10w30 in them from the factory... Hope it helps... I have ran the oil in the winter in all my psds for years...
Last edited by KCLawnTamer : 11-13-2008 at 07:06 AM.