What is reasonable compensation? Or is the mechanic correct?

Took great condition 2001 4D S40 w/no issues for regular oil change. Charged $200ish for "full system engine flush" due to "oil being like mud, thick like sludge". Same mechanic changed oil 2mo prior. Drove 20min for car to overheat. Wait 40min, pop hood, see no oil or coolant in car, BONE DRY. Now mechanic wants to charge me to replace radiator, turbo tank, water pump "just so that we can figure out what's wrong; wont know till we replace these." Insists they filled all fluids, can't find a substantial leak to cause drain in 24hr.

Told me it's just a crappy coincidence. I think it's his fault and should be fixed, or car replaced for car of equal value. I don't know cars. Please tell me: Coincidence and my job to fix/replace? Negligence and his job to fix/replace?

 

If the car actually had no oil or coolant, you need to document that somehow (video - second opinion from another shop). In fact, I'd cut my losses and not do ANYTHING at the shop you went to previously - they are NOT honest, or at the very least, not competent.

The one thing I'd add is that it's possible that the "sludge / mud" was due to coolant in the oil (from a blown head gasket, most likely). But any mech worth anything would ID that BEFORE they charge you to flush your cooling system and change your oil - they have to know it's a total waste of time. In this scenario, your oil level wouldn't be empty though, but probably overfull (with oil that looks like a milk shake).

 

Not sure if I'd have a lot of confidence in a tech who said he needed to replace parts to "figure out what's wrong". As with any fluid in a car, when you go to zero the first thought is the fluid has to go somewhere... The chicken/egg problem is did the car overheat causing the head gasket to fail or did a head gasket failure cause the car to overheat? You didn't mention if the car was in running condition or not but seems a first step would be to change the oil and fill the coolant level, properly burping the system and see if any leaks show up. Next is to run standard head gasket tests like looking for frothy oil, a compression test, a test for HCs in the coolant etc. Its quite possible the water pump did in fact fail allowing the car to overheat which can take out a head gasket / cylinder head. The coolant overflow cap is the pressure release mechanism so that should have popped before the radiator or overflow tank blow out. The head gasket issue would cause the oil milkshake and can allow some oil into the coolant passages or into the combustion chamber (a simple check of the plugs will give some clues).

I'd want to know more about what other clues are showing up...