Well, I may be late to the party but I'm here now! I dont belive in the gm 'piston slap' excuse. I don't believe 10 psi of oil pressure at hot idle is 'normal'. And I have personaly seen the real causes for both issues. Several times I was quoted a new engine install from the dealer if it bothers me so much.
Cam bearing and cam- maybe not much of a problem in the real world. But most people think it is. If you inspect your cam bearings and see copper color you assume they are bad. This is NOT the case on a modern ls engine. The cam bearings are installed at the factory and then line honed before cam install. This is the cause of the copper color seen and is not in any way an indication of a bad bearing in this engine. The myth comes from older engines that had an older style of assembly procedure. My cam and bearings were still at stock measurements despite low oil.
And for piston slap, my pistons were perfectly round. My bores had no measurable ridge and no marks whatsoever. Real piston slap would be most evident near the bottom of the cylinder so that is where I checked first in several ls engines. And never have I seen any indication piston slap could be taking place. I have seen many ls engines (4.8 and 5.3 and 6.2) with over 250k miles and near perfect bores. A huge feat for such short piston skirts. Good job GM!
Good write up Brian. I have a couple of comments. I used to work at GM Technical Assistance and I'm quite familiar with these engines.
I had been told the story of cam bearings being line honed, causing the copper to show through, and t sounded like a good story and I believed it, and told others the same story. Then I found out that the copper is showing on the bearings when they are brand new out of the box. Agreed, the copper showing does not mean the bearing s worn. The line hone story does not hold water. The new design bearings are coated, no longer show copper.
Also, they are pretty prone to piston slap cold, particularly the 6.2. Usually putting in new pistons quiets them down.
