Mattax is right on about this. There's still a difference, and it can be important.
But more importantly,
it doesn't matter in this case
@Dave NEO 's engine is pushing 30 psi even when hot. His engine shouldn't be making any noise because of that pressure, it's high enough.
So the problem likely isn't which oil he's running or what viscosity it is, he should be looking for what/why it's making noise. Maybe the top end of the engine isn't oiling properly, or the valvetrain is out of spec, or the lifters are going bad, or the cam is going flat, etc.
