I wouldn't run 5w20 in your diesel. It may not seem like you are gonna have any problems, but trust me, there are problems that can happen that you aren't aware of until its too late. I run all amsoil products, personally, I like the 15w40 diesel and marine oil. You couldn't pay me to run lucas products, but thats because I had a bad experience with them.
Scott

 

I use Amsoil 5w30 HDD oil and like it much better then dino Delvac 15w40 or Rotella synthetic 5w40 oil. I also like the nice easy starts when its -20 below zero.

 

I don't have to worry about -20 bearly even 20 but i still like the oil. I am planning on having an analysis run on it in another couple hundred miles. Probably end of this week.