I am almost ready to fire up my 400 for the first time also. The Crower book says definately do not use synthetic oil for initial break-in. Also no multi-viscosity oils either. They say use a high grade 30, 40, or 50 weight oil and put in a can of GM EOS part #1052367. I am going to do what they recommend. Everyone has a different way of doing this that I talked to but I will go with Crower and keep my fingers crossed.
__________________
74 LEMANS GT 350 4SPD MAROON
|