Obviously you like to denigrate mechanics, it's obvious.
Not a mechanic, I own a shop and a parts store. What do you do for a living?
Experience does not mean that my guys can remember the head bolt torque specs on a M20 BMW motor, that's why we have AllData.
You obviously share your FIL's regret over spending too much money on a old clunker, next time you should have him ask for an estimate as required by law for repairs over $100.
I charge an hourly rate, and also use a labor guide to arrive at my labor charges. Just like the dealer or any other indy does. What you and others don't want to admit is that sometimes on an old car it takes longer than what the labor guide quotes for a job. For example, the fuel filter on a gas W126 takes much longer than when the car was new or else one can damage the other related components. Hence, I charge 1.0 hrs, if the customer doesn't like it they can go somewhere else.
I don't need to work on older cars and do it as a courtesy for established customers. Honestly, most people that drive an older MB have your penny pinching attitude and it's not good busness to deal with your kind.
Shame on me? Lol, shame on your FIL for not asking for an estimate. Sounds like his car was a good candidate for cash for clunkers.
Just because you can do repairs in your driveway doesn't mean you can dictate what a shop should charge based on how much a set of plugs cost at Wal-Mart and how long it took you to change them.
If you know so much about the auto repair industry, why didn't you do the work for him? Lol, because you don't have the proper tools and know how.
Go ahead and price out a four gas analyzer and a scope and get back to us.
