I use to always buy my vehicles from Fitzgerald's and before that Piper's. They never question the shade tree mechanics. They just do the warrantee repairs.
When I can't do the maintenance, I would use the coupons they gave me as a buyer. They have been awesome.
Autoserve had sold me a Jeep that will not pass inspection. The last two inspections, they would reset the OBD and have me drive to Concord and back. They will slap a sticker on it. The reason is that the diagnosis is 'general emission failure'. It could be anything. They could find it right off and fix it for a few bucks, or it could take forever to find and cost thousands.
I can always find another dealer as I am not planning on coming back.