The 15-40 is a good weight oil. Usually used in diesels. I use to use it in my International Scout IIs and pick ups. I used, for a short time the 20-50 but it circulates too slow especially in the morning, was harder to pump and I used more gas with it. 10-40 or 15-40 is probably the best weights to use unless its below freezing. Then I would and do use 10-30. When my new 292 is broke in it will get synthentic. Possibly Amsoil or Mobil 1. I have used Texas refinery and it worked very well. Its a moly based oil. Just my nickels worth.
