Radiator

I recently purchased a used Intrigue, and am having trouble ridding the cooling system of air. I did not get the owners manual. What's the trick?

I don't know about the 3.8, but I have the 2002 book for the 3.5 liter motor and it talks about air bleed screws. I don't know where they are, though. Look around for something that looks like an air bleed.

How do you know that you have air in the system?

Irregular temperature

The bleed valve on the 3.8L engine is located on the thermostat housing.

https://www.mygmlink.com/pdf/go2content/manual/US/en/oldsmobile/1999intrigue.pdf
Go to page 5-17