Hey smokin', I too will be building a SBC, hopefully soon, and I want an opinion. You mentioned some break in proceudres. I was always led to believe that breaking in with synthetic is a no no because its too slick and the rings would never seat properly. Is that an old wives tale that's not applicable with modern machining practices? Did I make this up or has nanybody else heard this? I'm going to run a roller cam/lifters so I shouldn't have any cam break in issues and everything I'm hearing is that old school break in of a motor doesn't really apply anymore. Break the cam in (if applicaple), put the motor through a couple of heat cycles, change oil a couple of times, re-torque everything, and drive it like you stole it-Aluminum Squirt
Well A.S, I have heard similar from "old hands" but unfortunately haven't polled anyone really on it.
I do have some oil usage on the 454, but, she's still really a young engine IMO (only arround 30 hours) and I suffered a major leakage this summer (oil filter got loose)so I really cannot define just how bad it is. It is looking initialy like about a quart over about 20 hours of run time, but don't score that as very accurate. I have no smoking or exhaust residue from it, just oil "vanishing" ...... It could easilly be vapor going up the un-baffled PVC and being burned there. I had some oil usage before the motor was rebuilt, a similar time frame, and not leakage
I have read where today's bore finishes are far smoother than they were 20 years ago and thus ring seal is almost immediate.
The folowing is stuff I have dug up for ya AS,
From Mobil-1's website FAQ area ....
Is it true that new engines need a break-in period using conventional motor oil?
That is a myth. In the past, engine break-in was necessary to remove any metal flashing (called swarf) or abrasive material left inside the engine after machining, as well as to allow the valves and rings to ‘seat’ properly. Today’s engines are built with much tighter tolerances, much improved machining and under much cleaner conditions compared to the engines of 10 or 20 years ago. Current engine-manufacturing technology does not require a break-in period using petroleum-based motor oils.
In fact, Mobil 1 has shown excellent results in industry-standard ASTM tests, most of which use completely rebuilt engines for each new test run. Mobil 1’s outstanding results in these tests demonstrate that proper break-in using Mobil 1 is not a concern. Mobil 1 can be used in an engine from the day you drive off the showroom floor.
Can I use Mobil 1 as a break-in oil for a rebuilt engine?
Yes, but the timing of your first oil change will depend largely on the quality of the rebuild. Due to the tighter tolerances and improved machining of today’s engines, the traditional concept of ‘engine break-in’ is not as critical. However, if the engine rebuilder is using older machining equipment or lower-quality components, abrasive material can be left inside the engine. In this case, you should use a short drain interval on your initial oil fill.
From elsewhere:
CathKen Enterprises:
COMMON QUESTION AMONG NEW VEHICLE OWNERS is about the effect of synthetic oil on engine break in. Many dealers, mechanics and owners recommend against using synthetic oil during break-in. They accept the myth that an engine does not break-in properly when using synthetic oil. When questioned about this belief, most reply that synthetic oil is to slippery and does not allow the moving metal parts to seat themselves against one another.
This is simply not true; one of the very best things one can do for a new engine is to fill it with high quality synthetic oil before it runs the first time. A half century ago, car and motorcycle engines needed significant break-in time and care if they were going to give relatively long and reliable service. This fact of motoring life was mainly due to the roughness of the finishes on the parts that had to work close together. Piston rings and cylinder walls, for example, were not as precise or smooth as they now are. It is this roughness that requires break-in.
There is more of the same out on the internet, I'm trying to find stuff not from the oil makers or dealers, but is hard to.
Personally, I don't think I have a problem, and I don't think you will.