Patman

Please read this thread here on the oil board:

http://theoildrop.server101.com/cgi/...c;f=1;t=000335

Terry is an oil analysis expert, and is trying to figure out more about the problem here.

Superman

i have noticed more piston slap..or it seems to me a knocking noise from the engine with different oils.. haven`t yet figured out which oils make more noise... synthetic is definately better as far as less noise.

RTCamaroSS

both my SS and my mothers tahoe has piston slap, i took them both to a chevy dealership and was told that it was normal. the tahoe im not worried about because its under warranty for 4 more years. but my SS, i am worried about, its out of warranty now, with only 34k miles on it. should i worry about my engine blowing up anytime soon? the previous owner used dino oil for 27k miles, then i started using mobil 1 until 34k miles, now im using royal purple.. engine is strong.. just hope it holds up to the abuse.

SJH

Patman, I have read your oil posts for a long time.
I commend you on your dedication to this subject.

Piston slap however is from piston to bore clearance.
The stock ls1 pistons are "cast" high silicon(hypereutectic) pistons.Clearance beyond .003 is going to make some noise when cold. It will not do any harm though.
Mine(98 model year), with ridiculous amounts of wear and tear from n20 and supercharged use, and even after treating my bores to a glaze breaker, still were under .004" clearance.
Yes they made noise after the 1st rebuild until warmed up.
Not a problem though for the engine.
If you have ever heard real racing pistons in a muffled motor when cold, you'll know what true piston slap is. You should have heard my big cube pontiac with .008" cold <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
Now the problem with the above linked theory is, ls1 engines from the factory use an aluminum bearing with a steel backing <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> .
There is NO copper layer like a tri metal bearing. Also the ls1 uses a center thrust main (#3).
All bearings are aluminum alloy with a steel backing from the factory.

Steve

SJH

oops, I should not have said "ALL" bearings were aluminum.
The cam bearings,at least in my 98, are copper alloy.
With all the cam swaps going on, I would not be suprised to see some copper showing up in oil analysis's <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
Steve