GM 6.2L V8 Issues?
- Thread starter D45
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pappawheely
Autonomous4X4
I'm a big fan of the 6.2. 
Many of the 6.2s have run 250k miles and beyond without issue. Some have had lifter issues with the cylinder deactivation technology GM uses. Ram uses a similar system in their trucks. You can get an aftermarket tuner to shut this “feature” off, but then you are still stuck with the lifters that are used for this application. Many folks have done a cam and lifter swap to get rid of this potential problem. Honestly I wish GM and Ram would throw this technology in the garbage can where it belongs. But that’s our government and the EPA at work where car makers are forced to squeeze out the last drop of fuel mileage.
Take a look at the 6.6 gas engine in the GM 2500HD trucks. It was designed more with heavy duty fleet usage in mind. Luckily GM skipped all the cylinder deactivation stuff and auto stop/stop start on these engines. The block, crank, rods, are all pretty stout and from everything I have seen these engines are performing very reliably with good torque. It will be thirsty, but unlike the 6.2 the 6.6 is designed to run on 87 octane.
I chose the 6.6 to repower my project truck that should be on the road in a couple months. I lucked into what is basically a brand new engine/transmission out of a new truck that was severely damaged on the way to the dealer and subsequently parted out. I think it’s going to be great. Good luck.
Take a look at the 6.6 gas engine in the GM 2500HD trucks. It was designed more with heavy duty fleet usage in mind. Luckily GM skipped all the cylinder deactivation stuff and auto stop/stop start on these engines. The block, crank, rods, are all pretty stout and from everything I have seen these engines are performing very reliably with good torque. It will be thirsty, but unlike the 6.2 the 6.6 is designed to run on 87 octane.
I chose the 6.6 to repower my project truck that should be on the road in a couple months. I lucked into what is basically a brand new engine/transmission out of a new truck that was severely damaged on the way to the dealer and subsequently parted out. I think it’s going to be great. Good luck.
daly
New member
Ford too now. Starting in 2021 F150s with the 5.0 have a version of cylinder deactivation. Though the Ford system will be a little different being they are a overhead cam engine.
Require?
It's what GM says in the owners manual. I've been guilty of running mid-grade in mine and it hasn't assploded yet.
I think the run of lifter failure issues were mainly from a bad batch of lifters that went into engines prior to late '22, but I can't say that with any certainty. We have a Silverado with the 6.2 which was built late in the model year. 16k miles and no issues so far.
All i can say, as a long time car guy, SCCA racer & instructor with lots of seat time in pretty fast vehicles., is the 6.2 with the 10 speed tranny is a silky smooth beast. So much fun to drive even in a full size truck.
plumber mike
Adventurer
07-09 were the only ones that didn’t have the AFM. I’ve got an old 08 creeping up to 200k. Broken manifold bolts were a chore, but no major issues. I fully expect the transmission to go before the engine
daly
New member
It doesn't. It's recommended, not required. Even says that under the fuel door. I had a 2020 Trail Boss with a 6.2. If you want the full 420hp you need to run 93, otherwise the computer will retard the timing and de-tune the engine to reduce or eliminate detonation (spark knock). But it can only do so much and it is recommended you switch back to 93 if you hear spark knock.
daly
New member
My 2012 6.2 didn't have AFM. As far as I am aware, the 6.2 in the trucks, didn't get AFM until 2014 with the restyle. The only 6.2s prior to 2014 to have AFM were in the fullsize SUVs.
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NevadaLover
Forking Icehole
The ethanol in todays fuel is good for around 3 added octane points, turning 91 into about 94.