I totally rebuilt my Lt1 which is now a 355. THe guy who is helping me put the engine back in said I shouldnt run fully synthetic because if its as great as they say it is then the rings wont seat right. I see his point on this. He recommended just running normal valvoline for 500 miles then changing it then running normal valv. for another 1500 miles. After that Ill prolly just run Mobil 1. Tell em what you think or any suggestions.

 

I was told you should break in a motor like that with Regular Oil 10W30 weight would be good.

Here is how I broke my motor in and its been working great so far with 10W30:
Primed the system
Started it and let it run for 20 minutes, then Drained the Oil and Changed the Filter.
Then I ran for 500 Miles and again changed the Oil again with a new filter.

Thats about it, I did change the oil a 3rd time after it reached about 2100-2200 Miles just for my piece of mind but I dont think that is necessary. Your friend is right, you Do NOT want to break a motor in with Synthetic Oil.

Hope that helps,

 

Chuck's right. Go with standard 10 weight for the first 500. Then, whatever you want. I went to Mobil1 synthetic after I hit the 500 mile mark.