The main reason for you switching to the 5-30 is for better flow properties. The oil is a multiweight oil so the actual weight of the oil when cold is 5. The 2nd wieght is warm temp weight. The 5-30 HDD is actually a much more stable product then the AME 15-40 Diesel marine product. The flow properties and protection are better with the HDD. You are very well taken care of with the HDD 5-30.
I Myself live in AZ and run the AME in my PSD, but I run the HDD in my gassers. Yes Diesel Oil in a Gasser!!
