I asked the above question as part of another thread but thought I would start a new thread here as I went off topic in the other thread. For example, there is an Exxon station near me, privately owned. How do I know he is complying with the Top Tier additives requirements when he fills his tank? Could he not just tell the tank truck driver to leave the adds out and pay less for his fuel? I have only ever seen one Top Tier station, a Valero, have stickers on the pump saying that they are Top Tier. I always use Top Tier listed stations for gasoline but I want to know what guarantee I have that privately owned stations really comply.