It does seem odd that staight 30wt isn't available. It took me a long time to get away from the old rule, 30wt summer & 20wt winter, but after making the decision to use the high pressure pump in the 428, I felt a need to try 10w30. It seldom gets to 1,000 miles on a change of oil, which may be a little over cautious, but with the amount of fuel I push through, I do what I can to prevent diluting the oil.