+1!
I'll add that in my experience, most of the guys (gals too!) working in parts stores are car guys. If they weren't, they'd be working at Target, Walmart or Kroger instead. Same $$$ earned.
They'll express the occasional really ignorant opinion about a brand of oil or filter, a grade of oil or a make of car, but you see plenty of that sort of thing even here, where we are allegedly so well informed.
You also never know where people come from or what education they might have, although you can usually spot an educated person in no more than casual conversation and while that person may lack credentials they may be a well-read autodidact.