Thanks for the heads up!

 

That sounds like the same TSB that's been out for while now. Engine misfire due to carbon buildup on the valves and valve seats. At first they thought it was weak valve springs and finally they decided to start replacing the heads.

I burn 93 octane in mine 100%. Every 3000 - 4000 miles I use a fuel system treatment and I blow the soot out of it regularly. I hope I don't run into this, but I am trying my best to prevent it.

The way I look at it, it will cost close to 4 grand to do a head job if I pay someone else to do it (assuming it's outside of warranty). So in the long run it's cheaper to burn 93 octane. It costs me roughly $3 dollars a week to burn 93 as apposed 87. 3 x 52 weeks is $156 extra a year. This is local driving to work and back and some trips out of town. Burn 93 octane or pay to have your head worked.

Newer models are not supposed to have the issue, but I have seen some reports of 06 models with head issues.

 

is this on the 4 and 5 cylinders or just the 5's

 

I always use 93 octane as well... its not that much of a price difference IMO, and if it doesnt cause issues and my motor is happier then its fine by me. I've done this since I did get "bad gas" one time in my camaro and needless to say that sucked.

Same with motor oil... Mobil 1 all the way... havent had any issues with the motor besides known problems that werent caused by "bad or low" oil.

 

I called my local chevy dealer... and he says it is only on the 5 cyl.. which I am not so sure is correct.... a little leary of knowledge.. anyway... the recommendation for hight test is that it burns slower and cooler than lower octane fuel therefore easier on the valves??? also what do you think of using a top cylinder lubricant like marvel mystery oil as a preventitive measure??

 

talk about contradiction. the owner's manuel indicates 87 octane, and the dealer/GM is telling you 93.

 

I dont know the only thing I know is I dont want mine to f up after warranty.Thats money I would rather put into my truck for my pleasure.

 

I had the same problem with unleaded before pcmforless sent computer programmed for mid grade. Ever since, runs great.

I did run into something wierd the other day though. As I was pulling into my driveway my engine died. Not sure why, any ideas?

 

did the CEL come on? did you pull a code?

 

is the road to driveway uneven? maybe the truck got an unexpected jolt or shock as you entered? sometype of safety default built-in? just thinking out loud here...

 

talk about contradiction. the owner's manuel indicates 87 octane, and the dealer/GM is telling you 93.

Agreed. I've had that code occasionally. Usually goes away after I put in some injector cleaner. If it causes a problem, GM should fix the motor so it can run on their recommended fuel. I now question other fluids they "recommend".

 

Does that injector cleaner really work. I jus thit 20k miles and i think it is about time to do it.

Does it kill performance with that injector cleaner in there? Do you have to drive the full tank with cleaner in there easy until next fill?

 

I put one bottle in every 90-120 days. It's kept the code away that I was getting. So I'd say it's working. I was getting the 5th cylinder misfiring code.

Put it in a full tank. I usually dump it in, then fill it up. The gas going in mixes it up pretty good. Then just fill up when you want to. But I try to run most of it thru before filling back up. That way the most of it gets thru before being diluted by more gas.

 

Does it burn up or poof smoke lol

 

Does it burn up or poof smoke lol

just burns up.

 

Wow, this is disturbing news. I thought I was ahead of the game as I have been running 89 octane gas since I got the truck. I guess it is time to switch to 93.

 

I'd say 93 octane combined with fuel system treatment along with an ocasional goosing will do wonders for the valve train, cylinder heads, pistons and exhaust. Keeps the carbon buildup to a minimum and will keep the engine fresh & peppy.

93 octane should burn a tad slower and more controlled. That's also why it keeps the engine cleaner too.

 

No way. I'm running 87 in it. At 60k + miles, any damage has already occurred to my truck. If it blows up, then I've got in writing (manual) from GM that it's okay to run it. They can give me a new engine and new written instructions.

 

I'd rather you didn't have any trouble, but if you did I hope it works out for you. If it happens, keep us posted as I'm sure you will.

Here is a decent article on octane and levels for different compression ratios:

http://www.faqs.org/faqs/autos/gasoline ... ion-1.html

Here is the definition of octane from Dictionary.com:

http://dictionary.reference.com/search? ... e%20number

 

When my 05 was in for the Passlock locking out the injection for 10 minutes, the tech recommended fuel treatment and what GM referred to as "top tier fuel." Googled this and found the EPA recommending these major manufacturer fuels with additives rather than discount fuel retailers.
I started using fuel treatment about once a month with the cheapest 87 fuel in town as an alternative.

 

Still haven't gotten it back into the dealership yet. I called to make an appointment but didn't talk to anyone. So i left a message but they never got back with me.

After i get everything straightened out, i plan on using an injector cleaner in it regularly, as a few of you have said.

And this is all happening around 38,000 miles.

Stay tuned

 

It figures that it would happen around 38,000 miles. Most of us with 06 or older trucks would be out of warranty.

 

Well its not just the 5cyl trucks , the very next day after reading all of this I was in town by the local dealer when my truck started idleing wierd and my engine light came on. So I took it in to the dealer and he said one of your cylinders are misfiring , Long story short he said they have to replace the valve seats.Well thank god for extended Warranty , but for this to happen at 75000km is still bs. Anyways I just kind of thought it was funny for that to happen the next day I guess.

 

I always wondered why GM recommends 87 octane gasoline in the owners' manual. Our trucks have high compression engines which need high octane gasoline. The reason we get as much power as we do from these relatively low displacement engines is with a higher compression ratio. Sure, the truck will run on 87, but we are now seeing that it doesn't run on it very well.

I can not attest to the validity of the next statement but it is something I heard. Apparently GM recommends 87 octane becuase it is the environmentally good thing to do. The reasoning behind it is that one can derive more gallons of 87 octane gasoline from one barrel of crude oil than they could derive gallons of 89 octane gasoline from that same barrel of crude oil. That's all well and good but not when it could potentially cost me thousands of dollars in repair work after the warranty is up.

 

The 93 octane won't make a difference except maybe hold the problem off a little longer. I've run 93 from day one, and had the problem at 36053 miles. Most people are reporting it a little sooner than when it happened to me. There is a very long thread started by Turbizzy I believe about it from a year or so ago. It's not only build up on the valve seats, or it wouldn't warrant a new head just a fuel system cleaning which is not covered under warranty. It is the valve seats being too soft, and wearing unevenly so the valves won't seat and seal the cylinder. Mine was cylinders 2 and 4, with 4 being the worst. If your manual says you can run 87, and that's what you wanna do go for it, cause nobody (dealership and GM included) can fault you for doing exactly what the manual says even if it was a dumb move on their part for saying it.