I just bought a new 2003 Ford Ranger FX4 Level II, which calls for 5W-30 oil in the manual and on the oil fill cap. No other oil is recommended for use, just 5W-30. From reading these forums, it seems that Mobil-1 10W-30 SSis thought to be a better built oil than 5W-30 SS. I was just wondering during the summertime what would the benefits of running a 5W-30 instead of a 10W-30 be here in the St. Louis, MO area (it does get pretty hot here). In the winter, I definitely will use 5W-30, as it should flow easier when the engine is cold. Thanks for the help! Chuck P.S. This is an AWESOME site!!!!