This is why I quit going to dealers for service. On ten different visits you'll likely get ten different ways of them handling it, ten different parts or materials and ten different experiences - in spite of it being there for the same needed service. In the string about oil one guy said his dealership forgot to tighten a bolt on his underplate, and they also skipped an O-ring and used an air wrench to tighten it so hard he couldn't get it off. I watched in horror once as I got out and allowed a technician to ease my truck into the shop and he ran my front bumper into a brick wall. I also caught them putting the wrong oil in an older truck I had. Keep in mind that while you're in the guest lobby/waiting room relaxing and flipping through a magazine they could be doing ANYTHING to your truck, and it just might be the wrong thing - or at least not what you wanted done.
One other thing to consider about those invoices. They are all printed to indicate that correct parts or oil was used, but I'll wager anyone here that if you walk out into the service bay each time you go in for service you'll find them - at least once in a while - using different oil than what the invoice says. Keep in mind that invoice is pre-written by the office lady and prints out the same for each customer, but out in the shop they are putting in the wrong weight oil in some poor fellow's truck.
