Originally posted by sbourg
You presented a hidden modification to the vehicle, and only experience with others doing the same in the past would give them a clue where to look. The specs for the car are indicated in the owners' manual, and you ignored them and did not inform the dealer of this. Suppose you had put 10W single-grade oil in the engine, would you expect them to automatically guess the cause of your high oil consumption and plugged cat as that?
It is your vehicle and your right to do with it as you want, but do the techs and yourself a favor - document everything you do that is not a specified action to the car, and show the list to the service manager. Don't assume to know whether what you did is causing the problem or not, and don't make them second-guess you. If it were my shop, I would charge the full labor rate for however much total time was spent.
Pheeww! Thank god it wasn't your shop!
BTW.... My advisor is nice, so he didn't charge me anything. I don't have starmark on the vehicle, but i've been to that dealership many times.