In the market to buy a used 2007-2008 Sierra/Silverado

GMCaldwell · September 4, 2014

Hello everyone, I'm new here and was wondering if you wonderful people cold provide some input. Due to my budget $10,000-$20,000, I'm looking to buy a used truck. I've been driving a little bitty Infiniti G35 for the last 5 years and its time to get a truck. I've been a member of the G35 forums and I'm very knowledgable as far as common issues such as various repairs in certain mile ranges, differences between engines and what to stay away from. I'm looking for 2wd or 4x4, it doesn't matter to me. I will be checking out the forums so if you gals and girls think of anything important in that year range, please let me know. This is a whole different world to me. Thanks

servantsalesmen · September 4, 2014

Welcome to the dark side my friend! I personally don't have any experience with the gmt900 platform (the model of truck you are looking at.) My only recommendation is go with 4x4 because you may actually use it once a year or so and if you need it, you need it!

GMCaldwell · September 4, 2014

Thank you sir. I had a Ford 4x4 before the Infiniti and loved it when I needed it. I may not keep it narrowed down to just those years. I might also look into older 2500HDs if I can find some within my price range. I've learned something new already, what gmt900 means. Thanks

servantsalesmen · September 4, 2014

Somewhere on this site there is a key of what the common abbreviations mean.

I personally have a 2004 2500HD (trucks built from 99 to 06 and 07 classic are the gmt800 platform.) My truck has had tons of issues in its life. I purchased it new in 03 and it has the 6.0 liter motor. The motor has never given me an issue (87,000 miles) but it has eaten two flexplates (big gear that moves power from engine to trans), has had brake lines rupture as well as fuel and trans cooler lines due to corrosion. The Guage cluster went out and the doors have always leaked.

So from my personal experience, I'd look more at the newer gmt900 trucks. Of course not all trucks like mine will be as bad as mine but the newer ones won't have the brake line failures. (Very common on gmt800 trucks.)

intheburbs · September 4, 2014

I'll open the can of worms. I'm looking at the same year/model range for my daughter.

The 5.3L engine in the Silverado/Sierra half-tons have Active Fuel Management (AFM). Googling "5.3" and "AFM" yields over 1.5 million hits. AFM shuts down some cylinders under low loads to improve gas mileage, but causes many of the engines to use oil excessively, and some fail prematurely. I have to admit to some leeriness about buying a used 07 or 08 with the 5.3.

The 3/4 ton trucks don't have AFM. My 08 Suburban 2500 with the 6.0L doesn't have AFM.

An older 2500 (2000-2006, platform designation GMT800) is also a very good choice. Depending on your priorities/preferences, though, I personally prefer the GMT900 for the newer features - back up camera, heated seats, remote start, power folding mirrors and power tailgate (in the SUVs). However, quite a few folks believe the GMT800 is superior to the GMT900 in terms of powertrain and reliability.

Regarding trim levels on both platforms, from bottom to top it goes LS, LT, Z71 and LTZ. LS trucks have cloth. LT and higher has leather seats. Ditto with the GMC Sierra, a twin/sister to the Silverado. The GMC trim levels are SLE, SLT and Denali. The Denali trucks are competely loaded, have different engines, and AWD, instead of 4WD with a 2-speed transfer case.

GMCaldwell · September 5, 2014

Awesome guys. This is exactly the information I was looking for. I heard about the AFM when it first came out and didn't think it was a great idea at the time, so I bought a 2007 F150 instead. I wasn't aware of the oil consumption issues that came along with it. I think I remember it being a choice as to whether you use it or not, if you choose not to drop down to 6cyl, does it still burn oil? This info right here gives me a great head start and I greatly appreciate it.

servantsalesmen · September 5, 2014

Actually, the AFM runs the truck on 4 cylinders. From the factory it can't be turned off (as far as I know) but if you get a blackbear tune, it is turned off. Also, if you are looking at the gmt800 trucks, the only ones I'd be looking at are the "classic" models. They were the last production rub of the platform before the newer one was phased in. Thw classics, being the last trucks, had most of the issues of the gmt800 platform ironed out.

servantsalesmen · September 5, 2014

And for more info on AFM, there are tons of threads around this site about it with loads of good information from real world owners!

GMCaldwell · September 5, 2014

And for more info on AFM, there are tons of threads around this site about it with loads of good information from real world owners!

Nice, thank you. ive been looking on cargurus and I've found a couple of 08 1500's I like, an 09 Tahoe LT1, and an 07 Avalanche LT. This will definitely help me with my decision as well as give me an idea of what to expect.

6.2max · September 5, 2014

There is nothing wrong with AFM.

Had a 2009 5.3 with AFM. Not one bit of trouble.

MaverickZ71 · September 5, 2014

There is nothing wrong with AFM.

Had a 2009 5.3 with AFM. Not one bit of trouble.

6.2max has been living a charmed life. I would tell GMCaldwell to run for his life, away from a used GMT900.

I drove a used 07 Silverado with an AFM 5.3L and also a used 08 Sierra with an AFM 5.3L before I bought my 09 Silverado with an AFM 5.3L.

The 07 had a bad AFM lifter making a racket--that's why it had been traded in. The 08 gave warning messages/flashing indicator lights less than a mile away from the dealer lot and limped back with low oil pressure. Later they replaced the cam/lifters/oil pump.

So we bought the brand new 09 and at 7500 miles/less than 1 year old it started drinking oil. Now with the AFM turned on, it uses oil about as fast as you could refill it. Even with AFM, it never got the 20mpg on the highway that it was rated at. More like 16-18mpg. It won't hardly run on regular gas anymore. Even with running good premium fuel and Chevron Techron FuelSystem cleaner, it idles like crap and throws warning messages/lights due to the oil fouling the spark plugs/oxygen sensors/catalytic converter and possibly some bad AFM lifters hurting the cam. All this on a truck with excellent maintenance, no racing, and no towing. Now we are having to book it into the dealer to have the engine rebuilt before the warranty runs out. The 2 mechanics who will work on it say "they all do that" in regards to the AFM motors. The service manager told me the same thing a couple of years ago, but I didn't want to believe it then. Funny thing, though--the salesmen won't tell you that there are any problems!

Friends and family members are trying to get me to trade the 09 in on a new 15. I have been a lifelong GM fan who knows what RPOs like Z71, LT1, LS6, WS6, etc, stand for. But I honestly have lost a lot of confidence in GM and don't trust anything with AFM anymore! A Ram EcoDiesel is sounding pretty good about now.

Daryl LBZ · September 5, 2014

Make sure you buy a DOD delete kit if your buying a higher mileage GMT900 5.3L...

intheburbs · September 6, 2014

Make sure you buy a DOD delete kit if your buying a higher mileage GMT900 5.3L...

This doesn't really solve the issue, does it? Don't the AFM engines have special lifters, and aren't those the problem? What little I've read on the subject leads me to think that replacing the valve train is the only sure solution.

I came across an '07 Avalanche with a brand new motor for a good price. Should've jumped on it.

Daryl LBZ · September 6, 2014

This doesn't really solve the issue, does it? Don't the AFM engines have special lifters, and aren't those the problem? What little I've read on the subject leads me to think that replacing the valve train is the only sure solution.

I came across an '07 Avalanche with a brand new motor for a good price. Should've jumped on it.

I think the delete kit comes with new LS7 lifters. I've posted a link to it before somewhere on here just don't remember where.

2017SierraSLT · September 6, 2014

This doesn't really solve the issue, does it? Don't the AFM engines have special lifters, and aren't those the problem? What little I've read on the subject leads me to think that replacing the valve train is the only sure solution.

The main issue is oil consumption, which is caused by stuck rings on the 4 cylinders that are deactivated. Some have experienced lifter failure, but electronically stutting them off goes a long way to keep the oil control in check. I tuned my brand new '13 at 1000 miles and haven't looked back. It has the same mileage, a feeling of more refinement, and more power.