Everyone I asked about the GM reman said it was as good as new if not better because it includes any updates to the motor.
They did not ask for proof of oil change, but the service advisor new I had it changed a couple times at their quick lube plus a couple of my own changes.(trying to clean out the motor) So in 8000 since I bought it, it had 4 changes, 2 they would have record of. More than enough. btw, the noises sounded worse with M1 vs conventional.
It a few visits to the dealer over those 8000 miles to get them to treat it as a serious isse, but once the decided it needed tore down it went ok. They actually only tore down the top end at first think it was the cam, but saw that the cam may have only been source of the tick and not the knock, so the rest the way down it went. In all, they had it 10 days. Diagnosing, tear down, talking with GM powertrain, etc.
I was very happy with the tech's work. Nothing under the hood looked out of place. Everthing was cleaned, straps back in place. It looked just like it did, except for a clean aluminum block.
