Rod knock? (with video)
 

I have a knocking sound which shows up after the engine is fully warmed up (see video). My fear is that it's a rod knock. I just picked the car up from Carmax and because I have the worst luck, I didn't hear the knock on my test drive. But I'm still in the 5 day return window, so I can take it back if I want. But I really like the car. And I have the famous Carmax warranty. It's actually double warrantied right now. Maybe I can get a new engine two days after buying it. They'd love that.

https://www.youtube.com/watch?v=-E63b9lDAbw

BTW, I did an oil change yesterday (Mobile1, 0w40) since I had no idea what oil was in the car. I only got about 6ish quarts out of the engine. After driving into work (30min) this morning, I didn't hear the knocking, but it seems to come and go anyway, so I can't rely on the idea that the oil fixed anything.

I'm having a post-purchase inspection tomorrow, so I'll know more by then. I know nothing of flat-6's, so I'm just curious as to what the experts here might think the knock is, and is it something to worry about.

update wnated
 

Any update from the OP?

Oh shoot, I forgot to update here. I got an inspection and it came back with a clean bill of health. The tech thinks the knocking is a sticky lifter brought about by sitting for extended periods. I'm going to run it for a while and see how it turns out. If something pops up, I have the extended warranty to fall back on.

Good to hear.

Google bore scoring on Porsche motors. Sounds exactly like that! Doesn't sound like a stick lifter at all to me....

Ack, I forgot to update here. It turns out that the noise was in the trans. The knocking completely disappeared when the clutch was depressed. Long story short: tried replacing the flywheel, which was slightly out of spec, but that didn't fix it. Upon disassembly of trans, found the 5th gear somehow spun on the shaft. Ended up with a new (rebuilt) trans shipped over from Germany. The engine was also scoped before tearing into the trans, and all the cylinders came back clean. Warranty covered almost 10K worth of work. I was amazed that there was zero push back from the warranty company.

Thats excellent!!