anyone have the scoop on the latest as to the engine noise that lasts for a minute or two at start up. I have a 2003.

My understanding is the 6.0 and 8.1 make some piston slap noise for 5-15 seconds upon startup but not a few minutes,Smitty

mine is an 01, 125000 miles no 5 minute noise at all, just while its cranking then gone.

just timed the noise at 73 * outside temp w/ cold engine and lasted about 73 seconds. I have been told by many many others w/ same motor that this is typical. Know that gm will give 100 K miles engine only warranty bec of piston slap. some have said bec pistons were ordered in metric and cylinders in sae or vice versa. some of my friends have opted for the 100k warranty. I am not sure of the latest was there litigation to resolve? etc. Should I get a free GM rebuild or $. there used to be web sited "like a KNOCK" obviously instead of ROCK w/ info.. I am not a GM hater & have a vette in the drive too. I have had many people come up to me and ask me how I made my diesel go quite. Real prob for me is the blow by and getting into my oil and shorting my expensive syn oil life. P.S. I love frankenmoth MI always went there as kid on way to Grayling and U.P. it is Christmas all year long thnx!!!

very common on the new generation (99 and newer) GM engines 5.3 6.0 and 8.1. usually worse the longer the engine sits ie the oil drains off the cylinders. it is a piston fit situation having to do with short piston skirts. GM has issued a bulliten stateing no fix should be attempted.

Don't know if its the same deal, I put 130K miles on my Tahoe (5.3) with M-1 synthetic and it often had the tap at start up and for up to a minute.

My wife wanted the Tahoe when i got my Duramax. She took it in for an oil change at a quik-lube. They told her that these motors wont make that noise with a slightly heavier oil than the 5-30 that is spec-ed. So for the hell of it I had them put in 10-30 Castrol Dino oil.

I hardly ever hear it tap anymore unless it has been parked for a week or more.

My 8.1 has some tap -tap noise goes away in a minute. I use a WiX filter that has an anti drainback valve. Seems to help. I also run 10-30 in the summer- fall.

Wannabe

http://www.pistonslap.com/index.html

Just turned 150k miles on my '01 8.1L. Sure it burns a lot of oil sometimes when it's pushed hard, but I read that there was actually an intake manifold bolt TSB calling for new bolts that would fix that.
Sure, it's also got a little bit of noise at start up too but I'm not all that convinced that a little piston slap is materially detrimental, if it is indeed piston slap and not just dry lifters/rockers.
Is it perfect? No. But "Mr. Goodwrench" is the last guy I want tearing into my motor, warranty or not. Not to mention all the other stuff they'll screw up while it's in their shop for a couple months.
Put some straight 30W or 40W in it (since you're here in FL), and see if there's a difference in the noise. Let us know how it goes.

I had an '01 8.1L and it always sounded like a diesel at start-up for a few seconds. I was told the aluminum block or heads(whichever) had to heat and expand to seal off something or other properly.

If you can't tell I'm not a mechanic.