Today i,ve gone to pass the periodic Technical inspection with my 6.2 . The smoke test has been incorrect.It has thrown a lot of black smoke when they have accelerate it with the vehicle stoped. The truck throws more smoke for the right exausht than the left. Finally ,how the Inspection Station was almost empty,with out more people than me,they have checked the truck with other tester engine, and then the test has been correct:Smoke opacity=1.94.(I think the limit is 2.5 for NA Diesel engines.) But the inspector has said to me that i,ll have to repair it for the next inspection.If they woulnd,t repeat the test,it would be incorrect. What can i do for get more clean smoke from my 6.2?It has a lot of coal in his exhaust and air intake. Should to help stanadyne or wynn,s additives? Thanks a lot for your help.