I have a 1986 Ford F-250 Lariat XLT with the 7.5 460 with a little over 100k miles. What oil should I be putting in it? The shop I brought it to put in 5w30. I looked at a similar question on here and there were a few different answers such as 10w30 or 10w30 HM. Or even a 50/50 mix of 10w30 +...