I use a quart every 500 miles, and have done so since the engine (1970 455) was rebuilt 10,000 miles ago. I use Valvoline VR1 10-30. I have a small amount of seepage from the rear seal, but not very much. I do not have any white smoke. My oil pressure is 40-50 at 2500 rpm.
Here are some photos of the plugs I just replaced; you may note the wet oil on the threads of a few of them.

Does anyone have any ideas regarding the oil use, or comments on the condition of my plugs?

 

Those plugs don't look too bad. You mentioned you don't get any white smoke; however, do you get blue smoke when you romp on it?

 

wonder if your rings are broke in yet.how did you break in the engine??if you have been babying it they might not be broke in yet.you need to go out and put the coals to it a few times

 

The engine was broken in on a dyno right after the build, but since then I have been very light-footed, only burned out once.
I will give it a shot tomorrow to see if I get any blue smoke, but I can say that my exhausts trumpets are very clean with no oil reside.
Maybe I am loosing more out of the rear seal when cruising than I can see. Most of my miles have been highway for extended periods.

 

What type of valve covers?

Many after market do not have baffling for PCV valve.
Sucking oil and going thru carb , very little smoke.
Check by putting an in line separator in. A 1/4" water separator will work.
Or check for a wet hose at carb, use a Q tip

 

This likely will not apply to your engine but I built a 455 with the W-455 intake and has the PCV in the intake. I did not use the valley pan gasket and the PCV was sucking oil. I had to take the manifold off and make a baffle for it. If you don't have the PCV in the intake this will not be it.

 

Warm the engine to 160 degrees. Then take out all plugs and di a leak down test of each cylinder. It will show you if you have blow by on the rings or a bad valve. Easiest way to eliminate a probkem. If you have 15% or less the problem would have to be valve seals.

 

I checked mine on my new rebuild and about 300 miles. 0 to 2% on all eight cylinders.

 

I would not worry about the usage. Open the 4 barrels up and blow the carbon out every once in a while.

 

I will check the PVC hose to see if it is wet tomorrow.
If it is the rings or valves seals then I am going to follow Eric's advice!

 

in general as far as the plugs they dont look bad maybe a little rich are they r44 or 45 may go to a hotter plug as far as the qt per 500 miles the leak down suggestion sounds good to me to rule out mech problems

 

My bet is sucking oil in between intake ports and heads. Last 455 I built did that shyte. I was using an Offy DualPort intake of questionable provenance and C heads surfaced just enough to true them up.

 

Update: the PVC was fairly dry.
I had a friend confirm that on quick acceleration a small puff of blue/white smoke was emitted. I could not see it in the mirror but my friend behind me saw it - he cannot remember which pipe it came from.