Poor MPG and High Oil Temp C-15

My 07 NXS normally runs coolant temps around 180 deg, oil temps at 200, if im pulling a hill it will go up, i have seen 230 on the oil but thats the absolute highest, if im watching and get the switch on, the fan will pull it down right away, my pyro rarely goes above 800 on the hardest hill, and I never see over 40lbs boost, mileage avs 5.9- 6.3, would like it to be a little better but not bad for now.

 

Well ,look it's Mr knowitall...( wanna be FW )

 

i got 07 pete with acert 475 with 18 speed and the sweet spot is at 12500-12750.my boost is at 48 .and my quarterly fuel report has started to show a steady climb in fuel mileage.i got 3.55 gears in rears.

 

Just a quick FWI there is no oil temp sensor on any Cat engine Peterbilt with the Namex guage systom (mid 05 and latter with digital odometer). The computer caculates the oil temp by coolant temp, oil press, and rpms.

 

i have a nxs c 15 475 hp 18 speed and i just replaced all my manfold gaskets know i have a hiss and cant get over 32 lbs of boost camps are all snug . anybuddy help me out.

 

When my MXS did this I found this being the problem.

When you replaced your gaskets were all the sleeves still attached to the old ones?

One of mine was missing and went through both turbos. Won't build much boost when part of the turbine wheels are missing!

 

I have a 2001 6NZ Cat set at 550. The truck runs good, 6.2 mpg. My oil temp stays at 200 unless in a good pull then it will climb to 215-220. Water temp at 185. I've had a couple people tell me it's running to hot, and should change the oil cooler. Any thoughts?

 

Ever figure out what was your trucks issue OP

 

A couple of things this could very well be. [1] I know this will sound obvious but have you checked your oil levels? [2] Where your running right now is the outside air temps quite high 90 f+ ? would be interesting to see if the oil temp does drop down again in the fall and winter. [3] How old is the oil ? Try giving it an oil change with a slightly different grade one for higher temps. some oils they put in are designed for low temps e.g 0 w 30, try using 5w 40 or 10 w 40 in the summer months see it this makes a difference.