Should get the X scanned if you have a misfire. Even if the CEL or SES lights are not on the DTC may be in shadow memory.

Start mine this AM at -22 ... Fired like a champ ... New battery and spark plug and since valve cover gasket changed and cam sensors replaced ... misfire no more :-)

Oil in the plug hole was the winner. One of the cap screws backed off and the seal spewed oil all over the valve cover. I soaked it all up with some rags and replaced the plugs.

Battery was tested at 25% life left, so I will probably get a warranty unit.

Be sure to exchange your battery with one that has equal to or greater specs than the original and one that has the vent connector for the hose to the outside.

Looks like this is turning into a head gasket problem. I have a few theories as to why it didn't start and what has lead to today's fun incident.

1. I had a USB charger plugged into the rear cigarette socket which may have discharged the battery just enough not to start on a -2F day
2. A few of the spark plug holes were filled with oil from the leaking valve cover bolt seal. This happened on both sides. Interesting that both of these backed out between cylinders 2-3 on each bank. Perhaps this is the area that sees the most harmonic vibrations on the valve cover.
3. Girlfriend drove the car today to her work 30 minutes away. Car pissed oil all over the passenger side of the block and is now farting out blue smoke. I think the head gasket has popped, or there is a hole in the side of the block somewhere that I haven't seen. This is probably why it didn't start the other day. Low compression. It's definitely misfiring but there isn't the characteristic "knocking" sound of a soon-to-be dead engine. Oil was 3-4 quarts low when I filled it up after the tow truck dropped it off so I could drive it into the garage. I think she may have shut it off a mile too late after it started spewing smoke... who knows. Should be an expensive endeavor to get it fixed...

Check valve cover gasket... Especially if oils are inplug and check your camsensor position if there is oil there also... Had the same symptoms and this is fix following the changed and repairs of those.... You will have to wash all the engine and see from where exactly oil are coming from first...this is a $1.5k fixed T the garage if not DIY

May be there is a shortage somewhere.Mine got one so I just unhook my battery when I do not drive the car for over 24hrs otherwise my battery dies although it is almost brand new.

You could had a a frozen CCV system. That would account for the oil in the engine. Google this to find info on this.

Does this happen on the V8s?

For V8 most of the time the rubber membrane for the CCV gets torn and you get a high vacuum in the intake manifold causing it to suck oil into the engine cylinders.

https://www.youtube.com/watch?v=kKNeN8tR3wM