Additive? I used Mobil 1 5w30 Extended Wear non-synthetic oil for break-in. If it was coolant where would it be getting in...head gasket? I guess I'll watch my coolant level closely...
Its going to be near impossible to know exactly as some of the engine oils have cleaning additives that can be picked up by the oil analysis as sodium, it could also be cracked head or leaking head gasket (which I hope is not and if so I'd think you would know). What I would do for peace of mind is send in another oil sample PLUS the same oil straight out of the bottle to see if sodium is present in the oil before it goes into the engine. The sodium number looks low and if coolant is getting into engine I would check the cylinder heads I recall an article from Amsoil customer with the same situation he even watched the coolant level and never noticed it go down but sure enough he re-tensioned the cylinder head, sent in another sample and problem solved well ahead of any major issues.
Call them. The guys at Blackstone will be more than happy to talk to you about the analysis. They can tell you all the possible sources and where it might have come from and how to check whatever. As far as oil out of the can, they are familiar with most of the popular formulations.
All good suggestions. Initially I did have to add a little coolant but attributed that to displacing air after the first few hours of running on this build. Thanks Quick, I followed your suggestion and called them just now. I failed to tell them that I had the Mobil1 "5000" (accidentally bought that) and when I told him that he says "ahhhh, ok...that completely explains the sodium appearing at those levels." He said that oil is not actually Mobil1 and it has a large amount of sodium as an additive, more than most. He is going to revise his comments and send me a new report. Now I feel a little better! Thanks guys!!!
Blackstone Labs is awesome. Well worth the dime. By the way, if you were to blow enough coolant into the oil where you noticed a level change in the coolant, your oil would look like a bad milk shake.