Advise type of oil for a 2003 C-15

I would be a little concerned about oil consumption since he was using 2 gallons at a time. One is usually the normal rate with an oil change. Have you ran it enough to see about oil use?

 

I'm with KW600 and some other posters. Lucas is not necessary. I was using it, now I don't. I don't see any manufacturers of these hard working and expensive power units recommending adding a gallon or two of additives. My engine is a DD60, 14L. It hates Delo oil, gets loose and rattles sounds like death is coming soon. Likes Rotella, Castrol, but I just tried the Mobil Delvac and it's way ahead of the pack. Quiet, smooth idle, good viscosity after running 8 or 10 hours. My engine doesn't use any discernable quantity of oil in 15,000 miles of hard work, which I like. I do PM's at 15,000, by the way. I'm with Rollin Coal - might be excessive, might not, but it's my Freightliner and that's what I do. My truck, my choice. Best. By the way, have you called Caterpillar and asked them yet? Might be a good idea.

 

We have one truck that uses 2 gallons of Lucas but that is to keep the oil pressure up

 

I believe in Rotella T, I'm sure there are better but it's always done a good job for me. That being said I'm not a fan of swapping oil brands on an engine with several to high miles. I would stick to Mobil. I wouldn't use Lucas unless I had oil pressure issues. If so I would look at the bottom end top half of the rod bearings would be a place to look. They always wear first and will tell you if you need a bottom end done