help my 8.1 engine will not pass emissions test in canada

JC, before I retired at work (I'm a retired truck driver) he had a diesel motor that couldn't pass inspection. Our mechanic had me drive this truck until it warmed up then I drove it into the shop and our mechanic had me max out the engine RPM (told me not to let off the throttle) then he poured 1 quart of transmission fluid somewhere into the engine I couldn't see where need help here! And it cleaned up the emissions to where it passed with flying colors!