I just brought this truck and it has 131000 miles on it i would like to run synthetic oil in it but i have no idea what it has been used in it.

what oil should i run in this truck? i plan on towing a fifth wheel trailer about 13000 lbs.in the future.

what other suggestions should i do to prepare this truck for towing.

also how can i tell if its a 2004 or 2004.5

thanks in advance.

 

Any oil you want with the proper rating and weight.Amsoil,Rotella,Delo,Royal Purple,Wally World Super Tech etc.Tag on d//side valve cover could say 305 h.p 555 lbs of torque(04) or 325 H.P. 610 lbs of torque(04.5)

 

As above: Any syn mentioned above is good if meets cert. requirments
5 - 40 is fine.