I you go onto any of the Suburban/tahoe chat rooms, you will find that many people are *****ing about "piston slap" on the 5.3 and 6.0 engines. GM says it is normal, but from what I heard, it is from the piston skirts not being long enough on these engines. GM has a revised piston they say corrects the problem, but there is no recall on this because they say the "piston slap" won't effect wear. I don't own one of these engines, but I do know that there are a lot of pist off/concerned GM truck owners with these motors that don't seem happy.

With 40,000 miles, mine knocks quite a bit for atleast a minute or two. It seems to be getting worse as time goes on. It used to only do it in the mornings but now it does it after just letting it sit for an hour or so. With all this noise, I should have just got the Duramax! (I'm wishing I would have done that anyway!!)

I've heard some people that tried the top-end cleaner to reduce the knock but I don't think it helped much. There used to be a "GM Piston Slap" website but it doesn't seem to exist anymore. I know GM threatened the owner of the website on more than one occasion - not sure what ever happened.

ALITTLE THICKER OIL AND A/C FILTER HELP ALITTLE