[legion]

The mechanic that I actually take complicated problems to is paid his actual hours worked, which is a percentage of shop rate. Sometimes I pay him just to diagnose a problem for me, sometimes to do things that are beyond my ability. Either way, the way I see it, I'm paying for each hour of his knowledge it takes to diagnose a problem. He doesn't do the "change a part and hope that fixes it method". He's been known to pull out actual diagnostic tools beyond an OBDII scanner.