Replacing 2001 LQ4

[2500hdee]

I was able to eliminate my loud piston slap (in my '01 2500HD 6.0) using this procedure from a Vette mechanic from a GM TSB that I can no longer find. Mine was loud and after this procedure-was gone. I bought two cans of GM's top end cleaner Part #88861802-removed all the spark plugs-poured the cleaner into all 8 cylinders-let it sit 6-12hrs, put rags over the plug holes and turned the engine over for 20 seconds-those rags got covered in nasty dissolved carbon-replaced the plugs with NGK TR55's-changed the oil and filter. No more piston slap-it has now come back but is almost impossible to hear at 177K. I believe the original TSB called for 20min of idling after replacing the plugs but I wasn't comfortable with the engine idling with the oil possibly diluted so I skipped it. Worked great for me; I'll try again to find the write and post it up if possible