I bought my first diesel truck (6.7L) + had dealer change the oil + filter 3 months ago. The oil looks alot blacker now than it used to in my former gasoline truck engine after 3 months. Is this normal?

 

yes, it is normal for a diesel engine.

 

^^^ x2

It will be black within minutes of the oil change.

 

thanks,... for a bit I wondered if they had actually changed the oil at all

 

I guess it is normal for this particular diesel but not for all. I have had 2 Ford SuperDutys and while the oil did turn black quicker than any gasser I have ever owned, this Cummins I have now gets black almost immediately. The Ford took at least a few weeks to get that way.