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Discussion Starter #1
I always use top-tier level gasoline on my 2019 Traverse to help keep my engine clean as possible. I also plan to have a major fuel system cleaning each 50 thousand miles. I have been using Mobil gas since I got my Traverse. No junk gas...Who has had issues from using cheap gas
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Great post, and I'm not trying to be difficult here, but in DI motors top tier gas does nothing for intake valve cleanliness. As you quoted in the above article, Port injection motors provide the benefit of of washing the valve as the gas mixture is introduced pre-valve, but in DI motors there is no gas before the valve and only air and oil vapors from the PCV system. These oil vapors are what causes the carbon buildup on the intake valves in all DI motors including our 3.6's. The only way to keep the build up at bay, is run a can of CRC DI Intake cleaner thru the intake at every oil change and/or run a catch can setup to separate the oil vapors from the intake and keep them out of the intake all together. I walnut blasted my intake valves at 100K and honestly it's not that hard of a job as you can easily reach all of the valves (when the intake is removed) on these motors due to it's transverse mounting for the FWD setup. Therefore, to be clear, the top tier gases are excellent to run to help with deposits and keep your DI injectors and pumps running optimally, but they will do nothing for your intake valves.
 

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Great post, and I'm not trying to be difficult here, but in DI motors top tier gas does nothing for intake valve cleanliness. As you quoted in the above article, Port injection motors provide the benefit of of washing the valve as the gas mixture is introduced pre-valve, but in DI motors there is no gas before the valve and only air and oil vapors from the PCV system. These oil vapors are what causes the carbon buildup on the intake valves in all DI motors including our 3.6's. The only way to keep the build up at bay, is run a can of CRC DI Intake cleaner thru the intake at every oil change and/or run a catch can setup to separate the oil vapors from the intake and keep them out of the intake all together. I walnut blasted my intake valves at 100K and honestly it's not that hard of a job as you can easily reach all of the valves (when the intake is removed) on these motors due to it's transverse mounting for the FWD setup. Therefore, to be clear, the top tier gases are excellent to run to help with deposits and keep your DI injectors and pumps running optimally, but they will do nothing for your intake valves.
GM powertrain engineering has been on record saying they are less susceptible to buildup on their DI motors because they have the intake valve open while the injector is spraying thereby getting it some contact with the fuel as its atomized.

That said, I'll stifle my laughter at that statement and agree with you, based on mechanical logic and years of pictures (as well as catch can contents) of the LLT and LFX intake valves demonstrating otherwise. Now, on the newer LGX 3.6 they developed a patented oil separation system and a couple of guys on the Colorado forums have tried a catch can and it ended up bone dry. Also from my observations with my Colorado the oil change algorithm is even more conservative than on the revised-OLM Traverse. My Colorado, particularly in winter, barely gets past 3k miles before it's under 20%. Our Traverse still goes about 6-7k. Now, some have speculated since the PCV on the LGX keeps a lot more oil & combustion vapors out of the intake, it thus retains them in the oil and degrades the oil life quicker.
 

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nhrata01--I'm with you in the skepticism toward the GM engineer's comments; since the injection of fuel occurs at the last of the compression stroke (which enables the engine to run on regular gas even with a compression ration above 10:1), the intake valves are long since closed. That's a comical response from them. They must think we're completely oblivious to the workings of high-tech computer controlled internal combustion engines. Then again, maybe they were thinking of their Ford competition that has a combination of port fuel injection and direct injection; port to give just a minor amount of fuel washing over the intakes to eliminate the oil build up.
 

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GM powertrain engineering has been on record saying they are less susceptible to buildup on their DI motors because they have the intake valve open while the injector is spraying thereby getting it some contact with the fuel as its atomized.

That said, I'll stifle my laughter at that statement and agree with you, based on mechanical logic and years of pictures (as well as catch can contents) of the LLT and LFX intake valves demonstrating otherwise. Now, on the newer LGX 3.6 they developed a patented oil separation system and a couple of guys on the Colorado forums have tried a catch can and it ended up bone dry. Also from my observations with my Colorado the oil change algorithm is even more conservative than on the revised-OLM Traverse. My Colorado, particularly in winter, barely gets past 3k miles before it's under 20%. Our Traverse still goes about 6-7k. Now, some have speculated since the PCV on the LGX keeps a lot more oil & combustion vapors out of the intake, it thus retains them in the oil and degrades the oil life quicker.
Yup, it is laughable as I've personally seen my intake valves at 100K and they looked awful. Here's a pic of one of mine before the walnut blasting (sorry for the crappy image as my scope camera was not so great - have a better one now (y))
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nhrata01--I'm with you in the skepticism toward the GM engineer's comments; since the injection of fuel occurs at the last of the compression stroke (which enables the engine to run on regular gas even with a compression ration above 10:1), the intake valves are long since closed. That's a comical response from them. They must think we're completely oblivious to the workings of high-tech computer controlled internal combustion engines. Then again, maybe they were thinking of their Ford competition that has a combination of port fuel injection and direct injection; port to give just a minor amount of fuel washing over the intakes to eliminate the oil build up.
Yup, other automakers are going that route as well (Audi as well I believe) and the dual injector method seems to help as the small amount of port injection fuel does help. Wish my S63 motor on my 13' BMW X5M had those as walnut blasting these things is a engine out experience :oops:

I've gone ahead and installed a dual catch can setup and the amount of oil it catches is insane and it's probably good I did it now as it only has 20K on the clock.
 

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Discussion Starter #9
Great post, and I'm not trying to be difficult here, but in DI motors top tier gas does nothing for intake valve cleanliness. As you quoted in the above article, Port injection motors provide the benefit of of washing the valve as the gas mixture is introduced pre-valve, but in DI motors there is no gas before the valve and only air and oil vapors from the PCV system. These oil vapors are what causes the carbon buildup on the intake valves in all DI motors including our 3.6's. The only way to keep the build up at bay, is run a can of CRC DI Intake cleaner thru the intake at every oil change and/or run a catch can setup to separate the oil vapors from the intake and keep them out of the intake all together. I walnut blasted my intake valves at 100K and honestly it's not that hard of a job as you can easily reach all of the valves (when the intake is removed) on these motors due to it's transverse mounting for the FWD setup. Therefore, to be clear, the top tier gases are excellent to run to help with deposits and keep your DI injectors and pumps running optimally, but they will do nothing for your intake valves.
Its cleans part of the valve, not the entire surface.
 

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Its cleans part of the valve, not the entire surface.
Look at the picture of my valve - NOPE. The carbon build up was all around the valve and stem. There is NO washing effect or fuel that touches the back of the valve to provide any cleaning on our motors whatsoever. The only portion of the valve that stays clean is the surface that lies in the combustion chamber. On our cars the only thing top tier gas does is help keep the fueling system including injectors clean and functioning properly, it does nothing for the intake valves. Look at your quote above and it references issues associated with buildup on the valve and that buildup they are discussing is the back of the valve in the intake runner. This build up is due to the oily vapors of the PCV system and that is why I stated the only way to keep this from happening is a Catch Can setup and/or CRC cleaner at each oil change to help knock the build up down a bit.
 
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but Techron/cleaners do appear to help- when misfires are being set.
conditions are misfires and low compression in cylinder(s).
This because of carbon buildup on the lip/edge of the sealing/mating surface of the valve. (I Believe some call it sticky valves).

There has been several members who had low compression in 1 or multiple cylinders.
Running the cleaners was enough to clean this area and restore compression and get rid of misfires.

The memorable member-- had been told he had low compression in several cylinders.
get a new/used engine and the mechanic would install.
Forum members advised to run a bottle of Techron. He ran it. Good results.I believe he then ran CRC intake valve cleaner (or maybe BG?)
He reported vehicle was back to running normal.
Then he came back- I think 1 or 2 yrs later... and gave an update..... said the vehicle was still running fine.

from having an engine replaced-- to running a few bottles of cleaner. Paid off for him.
I know it wont solve everyones issues... but theyre worth a try.
 

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but Techron/cleaners do appear to help- when misfires are being set.
conditions are misfires and low compression in cylinder(s).
This because of carbon buildup on the lip/edge of the sealing/mating surface of the valve. (I Believe some call it sticky valves).

There has been several members who had low compression in 1 or multiple cylinders.
Running the cleaners was enough to clean this area and restore compression and get rid of misfires.

The memorable member-- had been told he had low compression in several cylinders.
get a new/used engine and the mechanic would install.
Forum members advised to run a bottle of Techron. He ran it. Good results.I believe he then ran CRC intake valve cleaner (or maybe BG?)
He reported vehicle was back to running normal.
Then he came back- I think 1 or 2 yrs later... and gave an update..... said the vehicle was still running fine.

from having an engine replaced-- to running a few bottles of cleaner. Paid off for him.
I know it wont solve everyones issues... but theyre worth a try.
Rbarrios, the Techron could be helping with the carbon build up on the surface of the valve (combustion side) and/or sparkplug as this can cause hot spots and cause misfires or knock/pre-ignition. I just don't see how it's helping on the valve seat/valve lip or the back side of the valve.
 

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Dave. Just out of curiosity. Do you use Dino or synthetic and do you rely on the OLM for oil change intervals?
 

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i would assume that if its not sealing correctly... any fuel in the cylinder is able to 'escape' past the badly sealing surface of the valve....
at least getting to some of the carbon and helping clean it up. once thats gone- the valve is able to close properly. compression back up. misfires stop. vehicle is driveable again.
But yeah- getting to the back of the valves once they seal properly.... diff story.
 

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Dave. Just out of curiosity. Do you use Dino or synthetic and do you rely on the OLM for oil change intervals?
Full synthetic now as I rely on the olm and dealer for changes as we got $17 lifetime changes at our dealer when we bought the car. For the first few years GM used a valvoline synthetic blend, but now use a GM Dexos that is 100% synthetic since about 2015. I've been tracking the olm and it is pretty spot on 6k each time and for full synthetic that is fine. I've also had a few oil analysis' done by Blackstone the last few oil changes and the oil is coming back good and still has plenty of life.
 

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Discussion Starter #16
Last note on this fuel system cleaning. I will do it often to access the valves etc. No on the fuel rail..My uncle is going to help me with this. The gas part is half the issue.
 
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