I recently broke in a 402 in my GTO. After the fire up, warmed up, cooled, warmed up again, drove a few minutes...change Rotella 15-40 out. Used GM EOS on initial oil. Put another EOS in on the Rotella refill. Set up a breakin tune on street with wideband, then left the shop.
Drove 500 miles before another oil change, but first 50 on a highway where I ran the thing up in a gear, then let her wind down against the compression. Switch gear, do it again. See-sawed and eventually was hitting full throttle on the upswings. I think traffic thought I'd lost my mind...
Kept DFCO settings on so she would cut fuel on decels. Set PE to keep 12.4 or so max fuel and pulled a bit of timing so she wouldn't go into KR easily (CR is 11.9). Closed loop set for leaner than usual. Fuel wash is the enemy!
After the 500 mile oil change stayed with Rotella 15/40, with 1/2 can of SLOB to boost zinc and stuff.
Now she has a more normal tune in her, and I get no oil smoke whatsoever at idle, mid or full blast. Have 2500 miles on it and gets stronger every time I drive it.
Worked for me. I hope the OP didn't really run 10 AFR in the initial. I chanced detonation to break in the rings, but thats what knock sensors are for, right?

 

Swamp Goat,

Thanks for all this. I'm afraid it had 10:1 or below for about 2,000 miles as evidenced by my dyo sheet 1st run!

While there is a good chance the rings are washed, for SURE the valve seals or something in the heads are leaking as evidenced by puddles of oil on top of the intake valves and lack of oil on the now-dry FAST intake floor.

I've decided I'll have to to redo the shortblock as well as the heads once and for all.... Your information makes good sense, I'll follow this advice when it's done with buddy and laptop in the pass. seat.... On a lonely road, LOL!

Where do you get SLOB and what does that stand for?

I guess GM has GM EOS

What do you think about Moly additive MoS2 (molybdenum disulfide) from T.S. Moly Lubricants in addition?

http://www.tsmoly.com/index.html

I've been running it on my 355 blower Z-28 both engine and rear end.

THANKS! Ram

 

Here is a link to God's own oil information site, BITOG: http://theoildrop.server101.com/foru...0&fpart=1&vc=1
This thread tells all about SLOB, but due to EPA rules, it was pulled from all retail shelves when the ZDDP cuts went into effect a couple years ago.
Big Lots bought it all. Depending on where you are, your local BL may have it for about a buck a bottle. Pink bottle, kinda ricer lookin' stuff, but analysis shows it is loaded with good stuff.
My understanding is the GM EOS has been pulled for the same reason, but I got mine from Scroggy Dickens. Some dealers may still have it.
All of the cam makers sell similar stuff. The guys and gals most affected are those running flat tappet cams or big spring pressures.

 

Swamp Goat,
Thanks a bunch. Excellent research! We'll chase some of dat stuff down!
Ram