Thick oil to solve valvetrain noise?

UPDATE:: Checked everything over again, should the rocker arms have a little play in them when the lifters aren't putting pressure on them? (non adjustable) - I found at least 1 rod that was definitely bent. I just ordered 16 new rods (for like $32 with shipping included) and I hope that fixes the noise... everything seemed to work properly other than that...

When you install the new pushrods put a little oil on them before install.

Do you know how to check the preload? Did you measure the pushrods that are in the motor or just buy stock replacements?