what kind of oil for new rebuild

DTK said
Not to start an additive war. You do not need additives. Good non synthetic oil already has all you need. Allot of additives create aeration. Air in oil is bad umm kay. As far as flat tappet statement, you are out in left field. The only additive you need for a flat tappet cam is the molly assembly lube the cam comes with. A flat tappet cam is broken in the first 20 minutes of run time. You NEVER let the engine idle on the first fire up. It should be kept between 1800 and 2500 rpm to break the cam in. Let the engine cool and reset tappets. It's done, it's broken in. the same holds true for Hydraulic cam but not roller. The other problem with additives it makes the oil too slippery ( yes you read right). Ok why is that bad? Glad you asked, What does oil do ? Ok it lubricates. It also is a coolant. Most people forget about this part. Like synthetic in a fresh engine is wrong. When oil moves over the crank as an example. It does not remove the heat from the crank properly. Rings do not break in properly. The list goes on. Its your engine do as you please. I built 1500 hp engines without a single additive. Never an issue.

I guess you haven't read anything in the past year then. Passenger car oils have underwent major changes in the past year and have lost the ZDDP additive package so they could meet the stricter 2007 emmisions rules. With out the ZDDP package COMP, Crane and others were getting calls saying their cams were wiping out lobes and through some research it was found that the oils dropped this additive package which helped to lube and stick to the flat tappet cams. Almost all if not all new car and really since the early 90's the engines came from the manufacturer with roller cams and the lack of ZDDP doesn't effect them like it does flat tappet cams. The GM EOS additive and the stuff COMP and Hughes sells adds the zinc back into the oil and it IS NEEDED for breakin and for normal use after that if you are using an EPA rated oil. If you run Royal Purple, Red Line, Valvoline VR1 or Brad Penn or another "off road" oil you don't need the additive.