I am so glad you mentioned top tier fuel! The mechanic said the same thing. I am a bit embarrassed that I didn't know what the heck he was talking about.
Well, I knew some companies had better gas than others... I knew some companies had more additives than others... But, I didn't know anything about Top Tier Fuel. I looked into the matter once I got home and sure enough... So, anyway.. learn something new every day... Lucky for me, Costco is on the list and there is right one right down the road from me.
So, to put the matter of a catch can to bed for once and for all (there are endless threads about the subject out there), and since the inception of the 6.6 there has been lots of questions about whether its built in oil separator is enough, I think I can safely say:
1. Almost any DI engine can benefit from a can.
2. The warranty issue cant be answered in a black and white way. You must figure that one out for yourself.
3. Almost every DI engine should be fueled with a top tier fuel if you can.
By the way, I had a can on my '17 1500 and still have two full mason jars filled with oil that I dumped from it over three years. I am a big believer in them. My quest was about this new 6.6. There is a lot of marketing material out there stating that there is a built in oil separator and they spent a lot of time and engineering trying to solve the issue.
For me, case closed.