440 Oil Weight
Never liked Quaker State oils. I remember dad getting a lot of engine work at the shop back in the late 70s and 80s when quaker state had some major quality issues. My son's high mileage Ram is all the previous owner used and was proud to tell us at 150k miles he only burns 1.5 quarts between oil changes. At 155k Kake started running RotellaT 10w40 and only burns .75 of a quart between changes and now has 210k on it. The engine itself is a lot quieter now, as well.
As for his 408 in the 65, he runs 10w-40 Brad Penn.