Update on my engine noise problem:

Before tearing into the engine to install new lifters, I decided to pour some Rislone Engine Treatment Concentrate into my crankcase to see if it would reduce my valve train noise.

Within about 20 miles of driving, the noise was slightly quieter than before, and ...

As suggested, today I pulled my oil filler cap with the engine running and checked my PCV valve. No difference in the noise.

I then removed the serpentine belt again and carefully listened to the engine in another effort to determine where the noise is coming from. I came away thinking that it ...

Thanks, Randall, for your reply to my post.

As you suggested, I double checked the balancer -- I can't detect any movement between inner and outer parts of the balancer, and noise is unchanged with the drive belt removed.

This doesn't sound like any valve train noise that I've heard before -- it ...

I have an engine noise of unknown origin on '95 Pontiac Bonneville with 3.8 liter V6 Engine. I am hoping someone can help identify the source of the noise for me. It sounds like belt noise to me, but the sound is unchanged with the serpentine belt removed, so it's clearly internal to the engine ...

I have a '95 Bonneville that has the OBD-1.5 system.
What PC-based scan software do you recommend for my laptop?
Do I need to buy any hardware other than a cable to connect 16-pin OBD connector to USB connector?