[wheelhopper]

When towing I my coolant runs about 195-200 while my oil gets about 5 degrees more. I also have a delete ,but stock tires/suspension.

 

[wheelhopper]

Makes me wonder if running a full synthetic oil would be helpful in the 6.4L?

Since the oil requirements in the 6.4 is 5w40 how could you use anything but synthetic. I have never seen this weight in conventional.

I just got back from towing my race car in its enclosed trailer. About 9klbs. My coolant or oil never rose above 205. This was going to part of WV where I had to drive up several long steep grades. My boost did make it up to 39lbs a few times. I just let off the throttle a bit to decrease boost and kept trucking.

 

[wheelhopper]

Not sure where I found that info. It was when I first changed the oil. Maybe it was on the filler cap. I just remember thinking that this was going to be an expensive oil change. I use 15w40 in my 7.3 all the time, so I would not have a problem using it if it was the recommended oil. Probably good to use synthetic anyway if you have your DPF and are getting fuel contamination.