Changed the oil, in the G8 and the Sierra.
While under the Sierra I found a torn halfshaft boot and a deep at the diff seal. So I ordered parts for that.
After the oil change I drove the G8 to get a log to get the bigger intake tube dialed in. I found it was worthless data because I've got a ltft bank 2 lean code... At idle my ltft for that bank steadily creeps up... I stopped looking after it crept up to +19% over the span of 8mins or so.
Last time it had that issue (it was after the car had sat for two months) I swapped plugs, coils, wires, injectors bank to bank with the concern that maybe it was a misfire issue, and the problem never moved to the other bank, it just disappeared.
I moved a propane torch around that head and never could get the stft to jump or lean out.
I thought maybe the check valved passenger oil fill breather was letting in too much unmetered air, so I put the oil fill cap back in and reconnected the intake line to the passenger valve cover. Didn't make a difference, if anything made it worse.
Way frustrating.