Doing a search, I found this thread on gminsidenews:
http://www.gminsidenews.com/forums/f53/3-6l-timing-chain-failures-due-redesign-98426/index4.html
Here's another post from XXSS on 2/27/11:
"...
I can speak from first hand experience that over 90% of the vehicles that land in my shop with P0008 current and require chains, also have low oil level (Most with none on the dipstick) and have traveled anywhere from 9000-20000kms between oil changes. The Camshaft actuators do require
oil pressure to function properly."
Apparently, GM went to a different timing chain/sprocket with smaller spacing in order to reduce noise, and that's what caused a problem. These chains may have been more susceptible to low oil/low oil pressure conditions.
Another search showed this link: http://gmpowertrain.ca/Product/3.6 LLT/LLT Camaro Summary.pdf
Talks about the 3.6, but no mention of a change. It DOES, however, speak to the problem design (see bold print):
"2010 GM 3.6L V-6 VVT DI (LLT) 3.6L V-6 VVT DI (LLT) CAR and TRUCK ENGINE
− Base engine in the Buick Enclave, GMC Acadia, Chevrolet Traverse, Chevrolet Camaro,
and Cadillac STS.
− Optional engine for the Cadillac CTS, CTS Wagon, and Buick LaCrosse
− Advanced multi-outlet high pressure fuel injectors that inject fuel directly into
the combustion chamber
− Variable, high-pressure engine-driven fuel pump for multiple injection events
− Stainless steel fuel rail
− Advanced engine control module (ECM) for direct injection control
− RWD applications matched to 6L50 six-speed automatic transmission
− FWD applications matched to 6T75 six speed automatic transmission. It is an advanced
transmission with clutch-to-clutch shift operation for front- and all-wheel drive vehicles.
The transmission's six-gear configuration allows for a "steep" 4.48:1 first gear, which
helps deliver exceptional launch feel, and a 0.74:1 overdrive sixth gear. Sixth
gear lowers rpm at highway speeds, reducing noise and vibration while improving fuel
economy. Also, the 6T75 offers automatic grade braking, shift stabilization and precise
shift control.
− New direct injection engine keeps oil life monitoring system
− Cam phasing coupled with direct injection further reduces cold start exhaust emissions
− Cast aluminum cylinder block and heads
− Double overhead cams with four valves per cylinder
− Cams driven by small-pitch, inverted tooth chain
− Variable valve timing with four-cam phasing for precise intake and exhaust tuning and
control
− High-power and high efficiency 11.3:1 compression ratio
− Cast aluminum polymer coated oil cooled pistons, with a fully floating wristpin
− Oil jets cool the pistons, while polymer-coated skirts reduce noise and friction
− Durable forged crankshaft, and precision sinter-forged connecting rods
− Cast aluminum structural oil pan stiffens the cylinder block structure and reduces noise
− Electronic throttle control with advanced integrated cruise control
− Reliable coil-on-spark-plug ignition
− Optimally tuned exhaust manifolds with close-coupled catalytic converters
− Composite camshaft covers are fully isolated and reduce noise
− Numerous other noise, vibration and harshness controls
− Exclusive durability enhancements and minimal maintenance requirements
− Manufacturing techniques refined for exceptional quality and manufacturing efficiency
Full Description of New and Updated Features
Base engine in Buick Enclave, GMC Acadia, Chevrolet Traverse, Cadillac STS, and Chevrolet
Camaro. Optional engine in Cadillac CTS, CTS Wagon, and Buick LaCrosse."
Here's a little bit more about a 3.6 redesign: http://media.gm.com/media/us/en/news/news_detail.brand_chevrolet.html/content/Pages/news/us/en/2011/Apr/0413_camaro_engine
Specifically: "
Compared to the 3.6L V-6 in 2011 models, the new LFX engine features:
- New cylinder head design with integrated exhaust manifold
- Improved intake port design and larger intake valves within the cylinder heads
- Longer-duration intake camshafts
- Composite intake manifold
- New fuel pump and isolated fuel rail
- New, optimized-flow fuel injectors
- Structural front cover and cylinder block enhancements
- Stronger and lighter-weight connecting rods
- Camshaft cap and throttle body design enhancements."
No mention here of a timing chain redesign, but this is 2012 compared to 2011 (supposedly after the 2010 redesign).
Okay, I'm done.