I have a 2005 Excursion with a 6L diesel. I had the truck for a year, and suffered a lifter failure (the roller was ingested into the oil pump via the pan intake)
Although the failure cannot be pinpointed, it was no doubt accelerated by the recirculation of BY-PASSED OIL. This occurred because the oil by-pass valve was MISSING from the standpipe in the oil canister.
The standard by which I am asking the dealer to accept some liability is the "plain view" of the pressure relief valve during an oil change, and the fact that their employee never looked into the canister to see the base of an aftermarket oil filter that was still sitting inside. For four oil changes, they were crushing the factory filter when installing it. I suspect they pulled the relief valve off after it became lodged in the oil filter when the filter was crushed during installation.
The dealer has a parts (Ford factory) and labour (repairs and replacement parts) guarantee. This is not a "warranty" per se, but a guarantee the job will be done "right".
Running the by-passed oil littered my engine with metal particles.
I realize that my post was pretty vague, but this is a negligence issue. They do a 60 point inspection for an oil change but apparently they can't notice a missing by-pass valve. Hence, the slow death of my Powerstroke and a big question of accountability!
How does one hold a dealer accountable for at least some liability?