Poor MPG and High Oil Temp C-15

Are you lugging it? High egt's?

 

2009 379 Pete C15 Cat here as well ... MPG 4.8 ave. Oil temp runs 225 - 240 .. Cooling fan comes in on it's own (I leave it in the auto position) when oil temp reaches approx. 235 - 240. No fault codes, Cat Tech scanned and checked settings etc. says it is running normally. HP output is setup @ 475 peak torque @ 1300 - 1500 range pulling. if it drops to 1300 or less it falls on it's face, also 18 speed trans, rear end ratios unknown "I never looked". Manifold pressures peak @ 30 Lbs. "unless DPF is burning then it will climb to 40 - 42 Lbs. and run like a 550 until the burn completes. Truck is ungoverened. current ODO 59,000 miles and change

I'll get an occasional "HEST" warning if I stop moving and come to an idle while a DPF burn is in process.

*Note Truck is equipped with a DPF
Company owners are NOT happy with fuel mileage it is nowhere near what the dealer told us we could expect (Three different drivers in this truck "me being the most recent" all ave. 4.8 - 5.2 no matter how we drive it

It should be noted I'm pulling hills more than I'm at cruise. Never been a huge fan of Cat Engines the darned things sound like they're going to fly apart at any moment.

Don't know if any of that helps but what you decscribe is how my C-15 has always performed.

 

How hot is it running my runs about 20 deg higher than coolant , coolant 190 oil about 210

 

Just leave the air to air on the truck and with an air hose blow thru everything. Just use caution so you don't blow the fins out of the radiator.

Wear a dust mask!

 

Part of your MPG is already stated by you. The ACERT is a different motor than any other CAT. The "sweet spot" for the most effiecent operation is about 1250-1275 RPM. You should be lugging the ACERT down to about 1150-1200 RPM then down shift. Cruise speeds need to keep the RPM around 1275 mark. The oil temp gauge or sendor could be taking a dump. You need to check it mechanically to be sure. If you are running a quality synthetic oil and your temp is actually 220-230* then you are still okay. But if you are running Rotella and the temp is 220-230* then I would seriously look into lowering the temp. You didn't list what the HP setting was on your MXS, but 42 is a little low even for a small HP setting. I would check for boost leaks at the clamps first.