New to Me Tow Ride

[mmandley]

Hi there guys. I wasn't sure of i should goto the Ford Forum and ask this but i hope you Diesel guys know.

I just got a 06 F350 Crew Cab 4x4 with the 6.0 and i was towing my boat today. 08 Moomba LSV apx 5K and i was realy expecting better mileage on the highway. I drove about 200 miles and only averaged 12.4.

Is this normal? I was expecting like 16. Everyone has been telling me id be getting 18.

Everything on the truck is working fine. Boost was around 12 driving and hit 24 when i punched it.

Is there a Diesel tune up?