Not 100% up on Rotella any more, but using a diesel formulated oil in a gasoline engine is very bad policy.
I’m not going to type out all the reasons why because a quick search of the web will explain it.
Think of this. You don’t hear of diesel guys running gasoline formulated oils in their engines do you?
Two completely different lubrication scenarios.
The oil probably isn’t your noise issue, but it’s still the wrong oil.
And 20 pounds of idle oil pressure is WRONG. That’s at the gauge. You probably have 5 pounds of pressure at the rods and zero at the rockers.
Go up a grade or two in oil.
