I have not heard any issues with the engine. What it is good, it is a 60 degree V6 which is the "natural degree" for for smoothness. I have driven this engine with a Automatic and it is indeed comparible to the uplevel 6-cylinders found in it's competitors, quick. I would expect the manual to more fun.
From GM

:
3.6L V-6 (LY7 Car/Truck)
Type: 3.6L V-6
Displacement: 3564cc (217 ci)
Compression ratio: 10.2:1
Valve configuration: dual overhead camshafts (4 valves per cylinder)
Assembly site: St. Catharines, Ontario & Melbourne, Australia
Valve lifters: roller follower with hydraulic lash adjusters
Firing order: 1 - 2 - 3 - 4 - 5 - 6
Bore x stroke: 94 x 85.6 mm
Fuel system: sequential fuel injection
255 hp (190 kw) @ 6500 rpm (SRX)
255 hp (190 kw) @ 6200 rpm (CTS)
255 hp (190 kw) @ 6500 rpm (STS)
240 hp (179 kw) @ 6000 rpm ( LaCrosse )
242 hp (181 kw) @ 6000 rpm (Rendezvous)
254 lb-ft (344 Nm) @ 2800 rpm (SRX)
252 lb-ft (342 Nm) @ 3100 rpm (CTS)
252 lb-ft (342 Nm) @ 3200 rpm (STS)
225 lb-ft (305 Nm ) @ 2000 rpm ( LaCrosse )
232 lb-ft (315 Nm) @ 3500 rpm (Rendezvous)
Fuel shut off: 7000 rpm for CTS/SRX/STS; 6700 for Rendezvous, 6900 for LaCrosse
evaporative system
dual catalytic converters
positive crankcase ventilation
Buick Rendezvous
Buick LaCrosse / Allure
Cadillac CTS
Cadillac SRX (base)
Cadillac STS (base)
Block: sand-cast aluminum (319) with cast-In iron bore liners
Cylinder head: cast aluminum (319 semi permanent mold)
Intake manifold: aluminum (319 Upper, 356T6 Lower)
Exhaust manifold: high-silicon moly cast iron
Main bearing caps: sintered steel (CU infiltrated)
Crankshaft: forged steel (1038V)
Camshaft: Cast Nodular Iron
Connecting rods: sinterforged steel
four-cam continuously variable cam phasing with internal exhaust gas recirculation (EGR)
pressure-actuated piston cooling jets
torque-based engine management system
Secondary throat cut inlet ports
Fuel rail w/ internal pressure damper
Internal front cover damper plates
cartridge-style oil filter
extended life spark plugs
extended life coolant
extended-life accessory belts
Replace Mobil 1 Synthetic Engine Oil with Mineral 5W30 GF4
Oil level sensor is deleted for 2006 applications
The 3.6L V-6 VVT debuted in the 2004 CTS. In 2005, a new six-speed manual transmission was added to the powertrain lineup. It is an all-aluminum, 60-degree dual overhead cam, four-valves-per-cylinder design. Like the 2.8L V-6, it has fully variable valve timing and a dual-stage variable intake manifold. The 3.6L V-6 develops 255 horsepower at 6200 rpm and 252 lb.-ft. of torque at 3100 rpm.
The Trannies
The CTS offers two transmissions. The Aisin six-speed manual transmission is fully synchronized (including reverse), with a single overdrive. This allows for lower propshaft speeds and improved noise, vibration and harshness. The transmission is rated for 400 Nm (295 horsepower) and its unique architecture is such that the gear inertias are lower, resulting in significantly lower shift efforts compared to conventional RWD manual transmissions.
The compact, state-of-the-art 5L40-E automatic transmission features a full complement of advanced electronic control capabilities. These include a shift mode button that allows the driver to select between "sport," "winter" and "economy" modes. Another electronic feature also is a first for GM: engine braking in all five gears, giving the automatic the same sporty feel as a downshifting manual.
SPECIFICATIONS
Overview
Model:
CTS
Body style / driveline:
entry-luxury, rear-wheel drive, 4-door sports sedan
Construction:
unitized welded steel body with direct-mounted front cradle and rubber-isolated, multi-link independent rear suspension assembly
EPA vehicle class:
midsize car
Manufacturing location:
Lansing Grand River Assembly, Lansing , Michigan
Key competitors:
BMW 3 Series, Mercedes C-Class, Audi A4, Lexus ES 300, Lincoln LS
Engine
2.8L VVT V-6
3.6L V-6 VVT (LY7)
Type:
2.8L V-6 VVT (variable valve timing)
3.6L V-6 VVT (variable valve timing)
Displacement (cu in / cc):
170 / 2792
217 / 3564
Bore & stroke (in / mm):
89 x 3.5 / 74.8 x 2.94
3.7 x 3.37 / 94 x 85.6
Block material:
cast aluminum
cast aluminum
Cylinder head material:
cast aluminum
cast aluminum
Valvetrain:
dual overhead camshafts, 4 valves per cylinder, continuously variable valve timing (VVT)
dual overhead camshafts, 4 valves per cylinder, continuously variable valve timing (VVT)
Ignition system:
individual coil on plug, individual cylinder knock control
individual coil on plug, individual cylinder knock control
Fuel delivery:
returnless sequential fuel injection
returnless sequential fuel injection
Compression ratio:
10.0:1
10.2:1
Horsepower (hp / kw @ rpm):
210 / 156 @ 6500 rpm
255 / 190 @ 6200
Torque (lb-ft / Nm @ rpm):
194 / 263 @ 3200 rpm
252 / 342 @ 3100
Recommended fuel:
unleaded regular
unleaded regular
Maximum engine speed (rpm):
7000 auto, 7200 manual
7000
Emissions controls:
dual close coupled catalytic converters, positive crankcase ventilation, inlet and exhaust cam phasers with internal exhaust gas recirculation (no EGR/AIR reqd.), evaporative emissions system
dual close-coupled catalytic converters, positive crankcase ventilation, inlet and exhaust cam phasers with internal exhaust gas recirculation (no EGR/AIR reqd.), evaporative emissions system
Estimated fuel economy
(mpg city / hwy / combined):
auto:
2.8L 18 / 27
3.6L 18 / 27
manual:
2.8L 17 / 27
3.6L 17 / 27
Transmissions
Hydra-Matic 5L40-E
Aisin AY6
Type:
5-speed electronically controlled automatic with lockup torque converter
fully synchronized 6-speed manual with single overdrive
Gear ratios (:1):
First:
3.42
4.15
Second:
2.21
2.33
Third:
1.60
1.53
Fourth:
1.00
1.15
Fifth:
0.75
1.00
Sixth:
----
0.79
Reverse:
3.02
3.67
Final drive ratio:
3.42
3.42
Chassis/Suspension
Standard/Luxury Package
Sport Package
Front:
independent, short/long arm, coil-over shock, anti-roll bar
independent, short/long arm, coil-over shock, anti-roll bar
Rear:
independent, modified multi-link, coil springs, shock absorbers, anti-roll bar
independent, modified multi-link, coil springs, automatic load-leveling shock absorbers, anti-roll bar
Traction control system:
full-range
full-range
Steering type:
power-assisted rack and pinion
power-assisted rack and pinion, TRW SpeedPro variable assist system
Steering wheel turns, lock-to-lock:
3.37
3.37
Turning circle, curb-to-curb (ft / m):
35.5 / 10.8
35.5 / 10.8
Brakes
Type:
power-assist – vacuum with anti-lock control and traction control
power-assist – vacuum with antilock control, traction control, StabiliTrak stability control, with high-performance brake linings
Rotor diameter x thickness
(in / mm):
front: 11.9 x 1.3 / 303 x 32 vented disc rear: 11.7 x 1 / 298 x 26 vented disc
front: 11.9 x 1.3 / 303 x 32 vented disc rear: 11.7 x 1 / 298 x 26 vented disc
Wheels/Tires
Wheel size and type:
16-inch x 7-inch cast aluminum
17-inch x 7.5-inch cast aluminum, optional 18-inch polished
Tires:
Goodyear Eagle RS-A, P225/55HR16, all season
Goodyear Eagle RS-A, P225/50VR17, all season
Dimensions
Exterior
Wheelbase (in / mm):
113.4 / 2880
Overall length (in / mm):
190.1 / 4829
Overall width (in / mm):
70.6 / 1793
Overall height (in / mm):
56.7 / 1440
Track (in / mm):
front: 60 / 1524; rear: 60 / 1524
Curb weight (lb / kg):
3.6L manual: TBD; 3.6L automatic: 3694 / 1676
Weight distribution
(% front / rear):
53 / 47
Interior
Headroom (in / mm):
front: 38.9 / 989
rear: 36.9 / 937
Legroom (in / mm):
front: 42.4 / 1077
rear: 37 / 940
Shoulder room (in / mm):
front: 56.6 / 1438
rear: 56.2 / 1427
Hip room (in / mm):
front: 53.4 / 1356
rear: 53.8 / 1366
Capacities
EPA passenger volume
(cu ft / L):
98 / 2775
Cargo volume (cu ft / L):
12.8 / 362
Trailer towing maximum (lb / kg):
1000 / 454
Fuel tank (gal / L):
17.5 / 66.2
Engine oil (qt / L):
6 / 5.7
Cooling system (qt / L):
11.7 / 11.1
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-----The orginal Mr.Goodwrench on the JBO since 11/99-----
