What grade motor oil should I use after rebuild?

[bennington28]

I dropped the rebuilt engine and I am ready to start her up. What oil should I use to break her in?

[Nick]

for car engines, i have no clue, but in aviation we use just straight mineral oil, no dispersents in it, so that there's big chunks of crap in the engine to help break in the rings and bearings

[brink]

This may or may not relate.... when I got my new bottom end, they just put in 10w30 dino oil. I broke in the engine sort of as described here http://www.mototuneusa.com/break_in_secrets.htm
I say sort of cause I had about 40 miles on the clock when I found out about it. I don't know what all went on with your rebuild, so I don't know whether to advocate that procedure or not to you.

Incidentally, at 500 miles I changed the oil again and put in straight 30 weight with this stuff called Hyperlube. It's FANTASTIC. I wasn't expecting any kind of power boost from it, I just got it cause it was cheaper than napa oil and a couple gearhead/racer friends recommended it for antisludge and wear protection. Couple days after the change I was driving and it just struck me, "man, my car is more powerful all of a sudden." Came to realize that the bottle gave mention of potential power increase. I swear, I've got like 10 more horsies under the hood with this stuff.