It's the age... not the diesel part so much, but there might be that as well. The dealer techs get trained on new models. So anyone that works there that has been there more than 20 years has had no "formal" training on anything with an ALH under the hood, and for that matter any of the AWP, AEG, AVH, AZG, etc. engines... and to be more broad, really the whole car because both the A4 and B5 platforms were being phased out around that time.
Then, you have to bring in the age of the individual(s)... they've been jaded by 20+ years of working at a dealer. They don't want ANYTHING that is "old", or "dirty", or "rusty" so they'll just gravy grab and toss the older stuff on the less seniority folks, meaning the ones that probably know as much about an ALH car as I do about botany.
Dealers can be a really F'd up place... why I don't work at one any more, or ever again. But some of their angst I get, and understand. It isn't always a good place to work.
I laugh because at one time a good friend of mine had a REALLY nice 1987 Supra turbo... and as anyone who knows that era of Toyotas knows, those in particular were not the shop favorite to work on. And ALL of the 7M-GTE engines blew headgaskets. Pretty much a 100% failure rate... sooner or later, it was gonna happen.
Well my friend's cherry low mileage one did eventually do just that. Only by now, because the car had been a pampered rarely-driven garage queen much of its life, it was some 20 years old. The only guy at the local Toyota dealer that actually KNEW anything about those, because he had been working there when they were new, was far into his retirement slide. He was not going to do squat but PDIs, brake jobs, and fluids and filters on newer (less than five years old) cars. Friend insisted his car would get "the best" care at a Toyota dealer. It ended in disaster. First, they tried to blow him out of the water with a ridiculous estimate. Then, when (to their surprise, and dismay) he agreed, they proceeded to screw that poor car up one side and down the other... that ended up with a tow dolly ride (courtesy ME) out of there. Turns out, the "kid" they had working on it had never ever DRIVEN a 3rd gen Supra before, let alone worked on one... and then they threw him into the 10+ hour head gasket job because they didn't want him taking their gravy work.
I worked with a pair of old retirement slide guys at Lexus, too.
