It took weeks to have vehicle initially fixed. Since then it has been running very rough (surging, RPMs fluctuating). I took it into the dealer per Cadillac Roadside assistance, they performed 15k mile maintenance and said "there's nothing wrong with it" and that apparently the 6.2L V8 is known to be a rough engine (not sure why it wasn't rough BEFORE the lifters broke). Apparently as the car had a few too many miles on it, Cadillac only allows 1/2 of the lifters to be replaced, not all of them. I guess when they receive a shipment of bad lifters they know they only went into 1/2 of the engine?

A few days AFTER taking it in for service, the check engine light came on and we received a text message informing us that the engine and transmission had to be serviced within 1 day?! Since that day (Saturday), it's been sitting at the dealer with no idea what's going on.

Tried calling Cadillac customer service, and as been happening since August, I cannot receive a call back from anybody. Received another worthless "we'll get back to you within 2 business days." I did receive a note from the Cadillac Twitter account reminding me that the dealer is independently owned (of course, Cadillac did insist I send the car there and not back to the GMC shop the did the initial "repair" of the lifters).