Will looking to see if there was a USA class action suit I did come up with this for all you 3.4L Alero owners... Did a search for piston slap and didn't see it in there...
http://www.classcounsel.com/news/gm.html
Green Welling LLP has filed a lawsuit on behalf of owners of General Motors vehicles who purchased or leased a 1999-2003 model with a 3.1, 3.4, 4.8, 5.3, 5.7 (LSI), 6.0, or 8.1 liter engine (includes but is not limited to the following models: Cadillac Escalade, Chevy Camaro, Chevy Corvette, Chevy Silverardo, Chevy Tahoe, Chevy Suburban, GM Denali and Yukon, Oldsmobile Alero, Pontiac Trans Am) and whose vehicles produce ?Piston Slap.? Piston Slap is a loud knocking noise produced during and shortly after engine start-up caused by the engine pistons knocking against the cylinder walls as a result of excessive clearance between the piston and cylinder wall.
Found a site for Americans with Dex-Cool problems to sign up too.
http://www.girardgibbs.com/dexcool.html