Have a new 05 SRT with approx 2000 miles on it. Plan to change the oil every six months/1500 miles. The Dealer(Dallas Dodge) recommends and sells Mobil 1 5W-30 fairly cheaply. The guy saying this is a Viper tech (and shop head there) who mentioned that most oil changes in the shop now use this grade of oil. With Texas weather, does anyone see any problems using this instead of the recommended 0W-40? I used this on the first change and have had no probs.