yessir, we need more input....

make
model
serial number
and which diesel engine does it have?
how many hours are on the truck?

generally any engine will use oil at first till it breaks in
and generally within the first 50 to 100 hrs of use it is required to change the filter and factory oil to the specified oil listed in the specs of the truck.

and just for curiosity's sake, what are the other oil levels in the transmission and hydraulic at? are any overfull?

until we have better information we all will just be rambling in general like i just did ;o)