Ok my brothers has on 06 pickup but with the 310hp engine (lly)and just today he noticed a clicking sound that is really noticeable The check engine light is on , and white smoke comes out at an idle when even when its warmed up. The clicking sounds like its coming right from the engine. And then i dont know if its just a coincidence but the low oil pressure light came on. Has brand new oil and it reads fine. The only thing he did different was use red farm diesel yesterday. But i doubt that would cause these problems. So if anyone can help me figure out what this is that would be greatly appreciated!!

forgot to say it only has 14,000 miles

if oil light comes on he needs to take it to the dealer... farm diesel doesn't matter to the engine just don't get caught with it.