I have a 2006 LLy with about 14,000 miles on it. The truck is a stock extended cab 8 foot bed, 4 wheel drive and I use Amsoil 530 Heavyduty synthetic deisel oil. During the day if i drive behind my truck you dont see any exhaust at all even if you floor it, you might alittle black smoke and then it goes away. But at night if you are the driver looking at the passengers mirror and if the car headlights behind you are in the rite spot you will see cloudy smoke coming out and does not stop until you pull away. When you floor the truck, it looks like you are covering the cars behind you with tons of smoke. My question is: Is the light just making the exhaust more visible to see than during the day? I also use an additive every other fill up, FTTF lubricity plus fuel power or total power during the winter monthes at 4 oz for a full tank. I was curious if that could be a possibility that you are seeing that exhaust at night? Its really weird and I was just wondering if anybody else gets this? Thanks for any information you can give me.