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V6 durability

15K views 26 replies 8 participants last post by  slls 
#1 ·
Hi, new to the forum
Just bought a 2008 LTZ with the v6 VVT motor. Is there any feedback on long term reliability of this motor? My last car with a 3.8 motor went over 700k kilometre. The car sees mainly freeway at 2.2k rpm. Is there any repair I should anticipate?
 
#2 ·
The 3.6L DOHC motor has only one major issue that can crop up. Namely using cheap oil and going long intervals between oil changes can lead to stretched timing chains, which is costly outside of warranty. Over time it will eat cheap oil and the resulting deprivation causes the oil-pressure driven chain tensioners to slack, and the chain will skip teeth.

The V6 needs synthetic oil like Mobil 1 and 4k-6k mile oil change intervals. The manual also recommends 89 octane for best performance and fuel economy, not regular. It runs noticeably more poorly on 87 octane. Take care of it and it will be rock solid, as well as achieve better than advertised fuel economy.
 
#3 ·
I woulda said what he just said but he said it first, so I'll just second it. :)
 
#4 ·
We're about to cross over 150,000 on our 08 LTZ V6 and couldn't be happier. I use Mobil 1 every 5,000 miles and have never had an issue with this engine. The engine has no leaks and runs just as smooth as the day we bought it.

I do run 87 octane gas and have never noticed any difference. On several occations I've run 89 and even 93 but the results for our car have been marginal at best.

For us the car averages 24.5-26,mpg with about 80/20 hiway city driving. We have gotten as high as 32 on long interstate hauls. So maybe the octane rating is not as important in hiway use.
 
#6 · (Edited)
I think my area just switched off of winter blend. I drove to my girlfriend's place over the weekend, 237 miles round trip after all was said and done, and got 27.9 mpg overall (hand calculated and corroborated by the DIC).

I was trying to be scientific about it to see what the car was capable of so here's the breakdown:

165 miles highway - cruise set at 65 to 72 mph depending on speed limit. Average speed showed 68 mph. No hypermiling or intentional drafting.

72 miles mixed city/hwy. Tried to drive light footed, but kept up with traffic.

Car has K&N panel filter, Mobil 1 5W-30, and 93 octane (I'm aware its not necessary).
 
#8 ·
No. dexos 1 was not used until the '11 MY. From the '09 manual:

Usage Fluid/Lubricant
Engine Oil
Engine oil which meets GM
Standard GM6094M and displays
the American Petroleum Institute
Certified for Gasoline Engines
starburst symbol. To determine the
proper viscosity for your vehicle’s
engine, see Engine Oil on page 5-15.

GM6094M
Use only an oil that meets GM Standard GM6094M.
• SAE 5W-30
SAE 5W-30 is best for the vehicle. These numbers
on an oil container show its viscosity, or thickness.
Do not use other viscosity oils such as SAE 20W-50.
• American Petroleum Institute (API) starburst symbol
Oils meeting these
requirements should
have the starburst
symbol on the container.
This symbol indicates that
the oil has been certified by
the American Petroleum
Institute (API).
Notice: Use only engine oil identified as meeting
GM Standard GM6094M and showing the American
Petroleum Institute Certified For Gasoline Engines
starburst symbol. Failure to use the recommended
oil can result in engine damage not covered by
the vehicle warranty.
Cold Temperature Operation
If in an area of extreme cold, where the temperature
falls below −20°F (−29°C), use either an SAE 5W-30
synthetic oil or an SAE 0W-30 engine oil. Both provide
easier cold starting for the engine at extremely low
temperatures. Always use an oil that meets the required
specification, GM6094M. See “What Kind of Engine
Oil to Use” for more information
 
#9 · (Edited)
@GolfTango - There's a reason GM changed over to Dexos certified oil. That recommendation is retroactive, they did not change anything about the engine. Running conventional cheap oil in the 3.6L increases the risk of the timing chains problem. They changed the recommendation for the same reason they altered the Oil Life Monitor for shorter intervals.

So the answer to Douglas92000's question is yes, GM recommends using Dexos 1 Certified oil in the V6. There are a list of approved brands or you can ask the dealer for a Dexos 1 oil change.
 
#11 ·
Well, I was just answering the question "does 09 require synthetic per GM". Short answer is no, GM does not "require" it. But the '11s up do if you want any warranty work approved. Now does your "engine" require it? I'd say, yes, absolutely! I'm always one to put quality oil in my cars. For my 2.4L, I started the dexos 1 as soon as it came out. I get it changed for $34.99 at my local dealer.
 
#13 ·
The complexity of the motor intimidates me. I have heard about these timing chains stretching. I will use synthetic at all times. I really like the car, right size comfortable on the highway and good in traffic. I was wondering if the 2010-2012 motor is the same as mine. I was considering buying a spare motor and installing it, if the need arises. Seems to me a motor swap would be preferable to the major surgery involved to change the two timing chains. Does a 2011 V6 just drop to my 2008 car?
 
#14 ·
All Malibus used the LY7 V6, so they're the same. However, I'm not seeing the benefit of an engine swap over a timing chain repair. A spare engine would cost way more than you'd save on labor, if it saves any.
 
#17 ·
Its like 10 extra dollars every ~5000 miles. I cannot see a valid reason not to use Dexos 1 oil when it's going to improve the longevity and reliability of the engine. Hell, the boost in fuel economy over conventional oil basically pays the difference.
 
#19 ·
The ECM program wouldn't prevent a swap though, would it? I thought they were updating the ECM anyway for just about any customer that came in with drivetrain issues.
 
#24 ·
The LT5 in the 91-95 Vette ZR1 was a DOHC engine and the output was unmatched by any V8 until the LS6 in 2002 and Cobra Mustang in 2003. However, the Mustang was supercharged. So you could argue Ford didn't match the LT5 until 2011 some 16 years after the last LT5 was built.

Then you have the whole Northstar engine program.
 
#23 ·
The reason for the pushrod V8s is their compact size and lighter weight. The 5th gens are some of the most advanced production motors in the industry. They are excellent for truck and muscle car/sports car applications because of the low-end torque output.

All of GMs 4- and 6-cylinder engines are now DOHC (save for the new 4.3L pushrod V6 for trucks based on the 5th gen V8s) and they're all very good. GM basically pioneered getting direct injection into mainstream vehicles, which is incredibly difficult with the NVH issues it presents and something other brands are still trying to master.

The first gen 2.0T with Direct Injection was by most accounts one of the best engines in the world for several years. It had utterly unheard of power and fuel economy that was years ahead of competitors.

And I could keep going.
 
#26 ·
Hmm seems relevant, yeah lets go back to the 90s, when Honda couldn't build an automatic transmission that would go 50k miles without self destructing. I guess we should say Honda can't build automatic transmissions based on that logic.

GMs DOHC engines, both I-4 and V6, are a big reason they pulled through their bankruptcy. I'm not sure it matters where Ecotec originated from since they're owned by GM--a global company--and plenty of engineering takes place stateside as well.

GM was actually the first domestic automaker to build such engines to rival the Japanese. Ford was building laughable motors before the Duratec 25 and 35 came out in 08-09, which finally mastered Variable Valve Timing at a time when GM mastered Direct Injection in Cadillac's 3.6L. Hell, Chrysler just released their first competitive DOHC V6 in 2011 and it's had its share of hiccups.

If you want to go back further, when the port injected 3.6L VVT was introduced in the CTS and later the Malibu/Aura/G6, it was well liked for its smooth and refined, yet muscular power delivery. Motor Trend even rated the Malibu LTZ V6 over the equally new Honda Accord 3.5L V6.
 
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