What is Recomended for cleaning out Engine?

[GMC Guy]

i got my engine finally put back together, and when i went to start it up, it fired right up

buuuuut.....i made a custom set of valve covers for easier valve adjusting, and within a few seconds of the engine running, i spotted some milky residue coming up on the rocker arms....

i got a few opinions and everyone said that it is just the oil pump picking up the milky residue at the bottom of the pan. that would make sense....

I NEED to know if there is any way of clearing all that crap out? like an additive or something?

thanks