My GM LQ9 6.0 would rattle at startup. “It’s normal”.. “They all do it” “it’s GM piston slap” That’s what everyone said. I had been using the Ultra for years. Pretty much since it came out. Until one day I decided to do a random hot swap with a different model fram filter. A TG. The noise was gone immediately! It was then I realized the filter was causing the “slap” all along. It’s been a few years since that, and still to this day no noise. Not even after sitting for months. Anyways, here’s the video that made me suspect a delay in flow caused by the multi layered ultra was contributing to the rattle.
Here is the video. People can decide for themselves if there is any validity.
I had the exact same issue on start up with my 4.2. Sounded like a metallic chain rattle with a Fram tough guard, no anti drainback valve on it either. Started using Wix xp and no more rattles.
Most people on here are concerned about filtering particles the size of a fleas foreskin , i just want good oil flow.