Marc95z28ConvM6

1. Do I replace O2 Sensor with motor hot or cold (like Plugs)?

2. Any other tips?

Injuneer

Its generally easier to break the O2 sensor loose if the exhaust system is hot. Get genuine AC sensors from one of the discount parts guys like Cromer or Slabaugh. Do not use anti-sieze. Handle them with care. Don't over torque them. Make sure the harness connector contacts are straight and clean.

pHEnomIC

If you are having trouble getting them out, autozone has a special socket you can burrow for free that is slotted so you slide it right over the sensor and break it loose from there. You can also use pb blaster to try and un seize them if they are stuck in good. It will probably ruin the sensors so dont use this if you are going to be using the same sensors. Clean the threads out after so the new ones can go in good.

Marc95z28ConvM6

UPDATE:
1. Went the Jason Cromer route to purchase the O2 Sensors. 850-243-8826 Less than $90 total for both delivered.
2. Used the Autozone Loaner 22mm - 7/8 deep slotted socket. (Loaner Tool)
3. Passenger side was tough. 162,000 miles. Probably the original.
Steps:
a. RustBuster
b. Unplug O2 cable
c. Socket on all the way
d. Very Long extensions with a swivel. From the top of the motor. Needed to use an Impact Wrench.
Fortunately the threads were fine. I understand if you heat the area with a torch, you run the risk of losing the threads. I'm glad it came out without using the torch.
4. Driver Side - Piece of Cake from under the car.

Nice to use the AC/Delco with the correct factory electrical connectors that clip in the brackets, keeping the wires away from hot spots.

Fingers crossed, that it will pass Emission Inspection now.

L8R