One thing to always remember, is that when you start your car cold, never put your foot down until it's warmed up. I never go over 2k rpm until the temps are all normal. I have noticed in my car the rattle seems to be loudest when VERY cold. As soon as the oil warms up, it gets much quieter. However, it's not piston slap though, because the block in 3rd Gen grows much more than the previous Gens. That means if it was piston slap, it would get worse as the cylinders grow after warmup. My guess it is has a lot to do with the oil temp. Once it warms up and thins out, it provides the proper pressure and flow to the Phasors, HPFP, chain tensioners, etc.This is a good sign. Maybe these engines just have a weird extended break in period.
IMHO this rattle seems pretty prevalent and I think by now we’d know if this rattle caused major damage.
I know some guys have been unfortunate and suffered major damage to their engines but it’s hard to point to the rattle as the exclusive cause of the damage.
I’m happy this thread exists and we’re sharing our experiences and ideas. I know reading these posts has given me much more piece of mind.