I am a new diesel owner. I have a 2002 ford f450 dump truck, It has 55,500 miles on motor. What weight oil should I be using for it. It has the 7.3L in it.

 

What does your owner's manual say to use? That's the fist place you should check.

 

I do not have an owners manual, I live in syracuse ny so need an oil that is good for hot and cold below zero conditions...

 

Winter in Syracuse. God help you. I found this, it has OM info and covers all the bases:

Powerstroke Engine Oil Rquirements - Superdutypsd.com

 

I always ran 15/40 no matter what the temp and never had any issues. Block heaters cure a lot of problems with cold starts on diesels. Had a boat with twin Detroits. When you fired it up on a 70 degree day it was ugly. It started right up it was just dirty like most Detroits. The marina restaurant had customers complaining. Put block heaters in it, electricity was included in slip fees, and it cleaned right up. Don’t worry so much about oil and just keep it warm.

 

15/40 Works great either a T6 or im a big fan of M1