asilverblazer

Can you sample the pooled liquid, enough to confirm it is oil? ...That its not fuel or coolant. Also, make sure combustion gases aren't entering the cooling system. Simply put, either oil being pushed up past the rings (this really isn't possible), oil leaking past the head gasket, oil leaking past the valve, oil entering through the intake air path. If none of this is likely - it may not be oil. What could be likely is the fuel injector leaking down. A puddle of gas would still smoke and rough idle. (Same cylinder has the same problem after injector replacement?) What is the crank time first thing in the morning, when the puddle would be present? Does it seem like the high pressure fuel pump needs an extra second or two to rebuild the pressure that injector 8 may have let bleed off? Check the fuel pressure via a scanner prior to starting the engine.

No.

I'm really curious to see what the O2 readings and timing looks like when you run it.

I have a hard time seeing oil from 'below' the rings 'pooling' in the cylinder. For an amount great enough to pool getting past the rings I would expect to see that same amount contributing to other noticeable symptoms, low compression, blow by, etc. You could try investigating for a stuck, gummed or carboned up ring, maybe an oil with different detergent strategy. Some other shade tree solutions like adding a detergent (or mystery oil) to the chamber and letting it sit, I've also heard of a heavy use of 'engine braking' to load the rings differently. I would first be looking at oil entering from 'above' via a head issue, or intake/PCV issue. I suspect that the oil is entering cylinder 8 combustion chamber at all times but is getting burned off during each combustion event preventing a 'pool' from forming and lessening visible oil burning smoke. This leads back to valve stems or PCV system as the only route for oil to enter the chamber from. I would expect a PCV issue to not be isolated to cylinder 8 though. Other considerations, how long does it take the pool to form? Could you look for the oil trail via the borescope? (Run the truck, shut the engine off, as quickly as practical, pull the plug and insert the scope and record to see how long and hopefully where from.)

Then why is it pulling timing so extremely at idle - but not at other more likely scenarios such as high load low RPM conditions? As a test, what would happen if the knock sensor was unplugged - revert to 'base' timing and see what conditions it defaults to and presents on the O2 readings?

There's a bunch of tea leaves that you've read, but in any case the delayed timing is unusual. Not sure how that relates to the rich at idle vs. 'normal' while driving. If you're in this deep, might be worth investigating, and re-learning the sensor. What have you got to lose? Plus, it properly fixes the timing cover leak.

The only problem I have seen this cause is longer crank times.

What are the conditions of this rich idle? Warm or cold engine? Run time? Does every idle look like this or only sometimes?

I had an alternator fail that was shorted internally in such a direct fashion in addition to the larger gauge cables that it appeared like a VERY dead battery. Granted I think the car did power up, it definitely wouldn't start. Rodent damage to wiring?

... I don't think he could.

Using experience to justify bad advice is lazy and typical of someone incapable of articulating why their advice is prudent. This immediately sets off the BS alert and the advice that followed certainly qualified. Asking an idiot for help getting out of dumb situations because he is an expert... at getting himself into dumb situations. Unless I've been living in an alternate universe - the first thing everyone does when getting into a sticky situation is shift to a higher gear . Of course not, the torque multiplication, mechanical advantage and finer control typically afforded by the lower gear is far better suited for this scenario. There ARE scenarios where a higher gear MIGHT be appropriate determined more by the drivers ability to control EXCESSIVE wheel spin versus applying torque to the ground.

Keep clearing the code and driving it to build more data on circumstances, the problem may become more constant, reveal itself or cause more symptoms that make diagnosis easier.

Some simple grounds from battery to engine, battery to frame, etc. using jumper cables might yield some clues. Battery condition? Alternator may have internally shorted - pull the power cable off the back if you suspect it.

People are stupid. "...I was a farmer..." Because that guarantees you're an expert? Sounds more like he was an indoctrinated idiot too dumb to try to learn something basic like mechanical advantage.

Desirable - as in does someone WANT one, aspire to have one. Could reasonably buy any car they want and CHOOSE these instead. I didn't watch the video, why did they win?

Are ALL injectors losing ground or just #7. Sounds like a wiring problem to me.

Agree 100% the buy backs are a prop to the stock price, in showing confidence, generating demand and thus inflating the price. The problem is the over focus on the shareholders to the detriment of the customer - the customer will only take so much pressure before they switch brands - and rarely switch back. Eventually, no customers means no sales, what value to shareholders is there then? Which leads back to the EV strategy, EVERYONE KNEW the EV customers didn't exist yet, but they went ahead anyway because the shareholders wanted it (Stock price increases at each press release), the release of the Hummer proved it (again, if you go back to the ELR coupe), but GM kept doggedly moving ahead with Cadillacs all electric future, Blazer EV, Equinox EV and again the ONLY EV with any kind of momentum was an on again off again mess. Further why was the success of the Volt/Bolt compared to the failure(s) of the Hummer/ELR not considered? Premium EVs weren't the answer. Cadillac is now in one of its weakest positions in decades, resurrecting aged platforms to rush back into a market the customers never left and are now searching other brands for. These are OBVIOUS MISTAKES (plus many others outside EV) that cost BILLIONS, people should have been fired, likely many people. GMs value as a brand to me exists only in what the assets could be sold for, because they obviously can't lead the industry.

Kudos? Are any of them desirable? Class leading (in any metric)?

Those are your ONLY options at GMC, Chevrolet and Buick - well, depends on what you define as SUV or CUV. The Traverse is essentially a minivan wearing an SUV costume, lower roofline, higher floor, upright grille and flat hood. Looks like a Tahoe performs like an Impala.

Mediocre, how much did they lose on the poorly conceived EV strategy? I wonder how much the stock price is being 'inflated' by all the buy-backs? Cadillac literally looks like a brand without a rudder, no clear goals or product direction - performance or luxury? I guess performance because we can throw a small block in whatever we can and call it a day. Certainly not luxury when a Denali or High Country is reasonably cross shoppable. The Celestiq - no way - no vehicle can command quarter million prices when something wearing the same badge is on the buy here pay here lot across town. Notice the 'base' Escalade doesn't even come with the 'leather-appointed' seating surfaces. Hummer EV - fail Silverado EV - fail Sierra EV - fail Bolt/Volt EV (The most successful EV cancelled, restarted, cancelled, whatever its current status it) Hybrids - none Sedans - none Medium duty - not anymore Minivan - none Coupe - none Convertible - none CUVs - 20+/- 6.2 Recall that landed squarely on the GMs highest seller - and specifically the fattest margin higher trims of the Yukon, Escalade, et. al. The most critical product line they fumbled big time. In the Escalade segment, are those buyers forgiving GM for a bad engine and patiently waiting for the fixes and dealing with the headaches? Nope, they dump them and go straight to the other premium brands. In the ENTIRE GM portfolio how many aspirational vehicles are there? Corvette, Escalade (quickly being superseded by the obvious better value Denali)... I posted somewhere else... what if Cadillac left the luxury game and became a performance brand similar to AMG or (gasp) Ferrari? Cut all the entry-level and base models from their line up and focus on the V-series or Blackwing or whatever they call it now. Of course, those would have the pre-requisite luxury and technology as standard equipment. This opens the floor for Buick to step in/up as the luxury brand (like they are in China), no 'performance pretenses' get rid of the 'entry-level' models with equally 'entry-level' power trains and become the Maybach to Cadillacs AMG. With those two brands effectively out of the way Chevrolet, the 'entry-level' brand has the floor to itself and GMC can take over as 'professional grade'. Now each brand has a focus, no in-fighting, clear direction, and customer targets. Just need to sneakily slide Corvette into the Cadillac brand and dump the vestigial script writing.

There is a big difference in motorcycles and vehicles - nobody needs a motorcycle, they WANT one. That WANT is the most powerful force to drive price upwards. I've hated every iteration of the Equinox, a prime example of GM laziness. It excelled at absolutely nothing, barely competitive by every metric. At least the latest generation looks decent. I want to like the Buick Envista, but that pitiful engine plus FWD only is a BIG NO for me, I don't care how good it looks.

I haven't seen inventory recovery from COVID. In the few random times I 'build my own' truck or SUV, no one has the exact one I want. GM has been working to lower incentives too for a long time. A $500 incentive isn't getting me off the couch to go truck shopping.

I read they were supposedly going for a retro look...

A running 4x4 here starts at 5K on Facebook. Off topic, Facebook and Craigslist here have been poisoned with ridiculous asking prices and no low-ballers junk sellers.