full synthetic oil?

X2^
I got a pretty hot 340. Im talkin bout 400 horse
I run mobil one 15w50 full syn and was recommended by my engine builder.
But id leave break in oil in there for 500 miles or so then change but its all personal preference.
But you want a oil with high zinc and phosphate ppm counts
The higher the zinc and phosphate count in ppm or parts per million is what your looking for.
A lot of the oils are geared to new vehicles and have low zinc and phosphate ppm levels due to regulations and emmision control statutes however there are oils out there geared towards flat tappet applications where a high level of zinc and phosphate is ideal for longevity of components.
Heres a list of mobil ones oils, but lucas has some muscle car oils that are pretty high in zinc and phosphate and so does royal purple. But as far as i know mobil one 15w50 full syn has the highest levels of zinc and phosphate in ppm.


[ame]http://www.mobiloil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf[/ame]