I took the truck in for an oil change and semi-annual service today (yeah, yeah, but it's cold, damp and salty under there, so I decided to let the dealership do the work this time). Anyway I bought the truck used a few months ago, reasonable mileage and good price, and it was given the once over and certified by the Ford dealership that the previous owner always dealt with (even though it's a GMC truck). So, I take it in to my local GM dealership and what should have been a 45 minute visit took almost 2 1/2 hours because of a sign in the customer waiting area "Customers are invited to visit the service bay and watch as your service is performed".
I jumped at the opportunity to get a good look underneath as well as examine the wheel-speed and O2 sensors and find all of the grease fittings. The mechanic was great, he took the time to point out where the bits I cared about were located (on the web, I found folks arguing about whether this particular model has 2 or 3 O2 sensors ... well, she has 4 and now I know exactly where they are) and he even brought up schematics on the computer for me to see how to get at the wheel-speed sensors.
All of that was great, but the big thing was what almost didn't happen had I not been there watching and asking questions. The rear differential plug was seized pretty good, so he stopped trying to take it off, and went to draining the engine oil I assumed he was planning to get back to it. We went over all of the grease fittings at the front end and he hung up the gun, but I asked about the u-joints on the drive shaft, so he checked and found a fitting at the rear end that he didn't know the truck even had. He finished up the work underneath and was about to lower the truck when I asked about the differential. He said he didn't want to damage the plug by forcing it, but if I really wanted it checked, he would try one more time, sure enough, once it was off, we found it was low on fluid, he was shocked that he got over a liter of oil into it.
Morals of the story:
1) If you can find a dealership or repair shop that will let you into the bay during service, take advantage of the opportunity to get some questions answered and to oversee things.
2) Don't assume the guys know everything, they're busy servicing umpteen different car/truck/SUV models and while there's a lot of overlap, if they're supposed to get a car in and out in 20-40 minutes, they'll do what they believe is right and potentially miss something.
3) Don't assume they have done all of the work you expect to be done, if something is seized, there is apparently a chance they will not risk doing damage by forcing a bolt or plug, but by getting them to make the extra effort, you could prevent costly repairs down the road.
4) There are better things to do at the dealership than reading a newspaper and drinking coffee.
