1998 Chevy Lumina Is this a cover up or what?

unusual engine noise" Was it there before the oil change if so they could have exaggerated it by leaving the oil drain plug off or an oil filter not tightened properly losing all the oil while the coolant flushing is going on-This is my opinoin

There was a noise, but I don't know what it was. I was going to ask my mechanic the about it the following week if it continued. I guess I don't have to worry about that any more.

I failed to mention in my first post that I keep records of my fill ups. I have been averaging 19.4 MPG for the last 6 months. On the fill up before the oil change, it was 19.6. This is well above the rating according to the Dep. of Energy's website. It was also running fine, not smoking or consuming oil.

Also, during their initial inspection, they found that it was about 1/2 quart low. After the damage had been done, they tried to claim that the oil was "barely on the dipstick".

I took the vehicle to the shop 5 days after my last fill up. So after 5 days and 120 miles I'm running on 2 cylinders? This really doesn't make sense to me, unless they ran it without oil.

I am also curious about how a coolant flush is performed. The shop claims that there is some kind of machine that is used while the engine is running. is it even neccesary to run the engine? If so, how long does the process take?

I also should mention that I will probably use the answers to these questions in the small claims case that will be tried within a month or so. I need to ask you what your qualifications are. How many years of experience do you have as a mechanic? Do you hold any certifications? Have you recieved any awards? Please be complete and specific in your answer. Thank you.

They use a coolant flush machine to remove old coolant and replace with fresh 50/50 mix.
This prevents coolant contamination in the environment, by removing old coolant and adding fresh coolant, without draining old coolant into container, for example. Coolant is dangerous and very toxic.

My view is they forgot to tighten filter, or drain plug and ran car with little or no oil. This in turn caused a main bearing, cam bearing, valve train failure, or damaged piston rings.

This would be 100% their fault, and rather than argue about it, they should try and come to a compromise with you about replacing engine, replacing with a used one for example.

The best evidence you can provide is to have your mechanic disassemble engine and find exact cause of failure.

Any reasonable person would conclude, on circumstantial evidence alone that:
1. Car comes to shop. Car is running fine with minor engine noise.
2. Oil is changed and coolant is changed.
3. Car is running on 2 cylinders.
4. Problem is a result of their negligence.
5. Conclusion is that they failed in repair and caused damage, and are trying to blame problem on "engine noise". If they were concerned about noise causing engine damage they should have refused to repair or had you sign a document ackowledging noise and that it "may" cause engine damage for which they would not pay for.

Thanks for your input.