My wife's 111k mile 2010 GMC Terrain just suffered a major engine issue last week. $1900+ dollars later, it seems to be doing OK, but that hurt. The 2.4 Ecotec suddenly started running very rough, noisy, and short on power. After a tow to the nearest GMC shop, the techs diagnosed a failure of one or both of the cam actuators/phasers. The timing chain, tensioner, and a fistful of other parts were all replaced. I asked the lead tech if this was an unusual failure for this engine type. He said he's seen it more than once. He couldn't say the exact cause, put if he had to guess, he'd put the blame on not changing oil frequently enough. He thinks DI kills oil, and maybe the VVT system is a bit of a weak link. For my part, I have my doubts. Aside from one or two oil changes in the first year with conventional, dealer bulk oil at 4k mile intervals, I've used synthetic Valvoline, Pennzoil Platinum, or M1 at 6000-7500 mi OCIs. That said, I'm spooked and will probably go to 4k or 5k OCIs until we unload the car next year. What do all of you think? Is the tech just speculating, or might he be on to something?