[MJ365]

Since I only put between 5-7000 mi (150-200 hrs) a year on my 04 since I quit driving it to work every day I run the Amsoil AME 15w-40 and change it once a year right before winter using Racor filters. It doesn't thicken up when cold like most others and starts cold better on my truck than even another 5w-40 I tried a while back. Works good for me as I don't have to change to a thinner oil in winter because of this. With no inductive heating my truck will start just fine down to zero, let it idle about a minute and then idle off down the road.

The 6.0 is famous for shearing oil down in weight. It will shear a 40wt down to a 30wt before the oil is anywhere near bad in other ways. My 04 with the AME @ 200 hrs isn't sheared down below 40wt (based on analysis) yet so it does seem to hold up well in this respect in my engine at this interval.

Another thing to consider. Changing oil based on hours or fuel consumption is a better way to determine change intervals on diesels. If you idle a lot or burn lots of fuel towing heavy all the time you will change more often using these guidlines. Total miles don't mean a thing. The trucks where I work would have over 300 hrs at 6000 miles which is too much when idling around a lot. We change @ 200hrs on gas and diesels and oil analysis supports this as being a good interval for both in our situation.

DISCLAIMER: These are my experiences, however there may be different results on other vehicles.