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6.2 engine fuel

Bherm

By Bherm
in Troubleshooting, Warranty & Recalls

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Kilgore Trout Enthusiast

Kilgore Trout

Posted
Posted

I definitely do.

 

I bought one of those clone Tech 2 scan tools for my 2007 Yukon.  I would set it up and watch the knock sensor and timing ****** functions on my 5.3L (LMG) engine while driving around town and short highway jaunts.  This engine has a compression ratio of 9.9:1.  Even around town the knock sensors were constantly lighting up with a corresponding timing adjustment.

 

What I determined is the tuning of the ECU has the engine "ride the knock sensors" for final timing adjustment.  There were times when I noted the timing was actually retarded to ATDC...

 

While I suspect the 6.2L engines (with their higher compression ratios) can run "safely" on regular gas, due to the sensitivity of the ECU and its sensors, you are going to sacrifice performance with lower octane fuels and I think are depending everything in the sensor loop to be working really optimally to avoid damage.

 

Where I live 91 is the highest octane I can buy from a pump.  The cost is always about +10% or less for 91 over 87.  When I do the math, in the big picture, it just isn't enough to worry about so I follow what the owners manual recommends.

swathdiver Senior Enthusiast

swathdiver

Posted
Posted
45 minutes ago, Kilgore Trout said:

I definitely do.

 

I bought one of those clone Tech 2 scan tools for my 2007 Yukon.  I would set it up and watch the knock sensor and timing ****** functions on my 5.3L (LMG) engine while driving around town and short highway jaunts.  This engine has a compression ratio of 9.9:1.  Even around town the knock sensors were constantly lighting up with a corresponding timing adjustment.

 

What I determined is the tuning of the ECU has the engine "ride the knock sensors" for final timing adjustment.  There were times when I noted the timing was actually retarded to ATDC...

 

While I suspect the 6.2L engines (with their higher compression ratios) can run "safely" on regular gas, due to the sensitivity of the ECU and its sensors, you are going to sacrifice performance with lower octane fuels and I think are depending everything in the sensor loop to be working really optimally to avoid damage.

 

Where I live 91 is the highest octane I can buy from a pump.  The cost is always about +10% or less for 91 over 87.  When I do the math, in the big picture, it just isn't enough to worry about so I follow what the owners manual recommends.

 

1 hour ago, Bherm said:

How many of you are using premium fuel on the 6.2 engine 

 

Those who run low octane fuel in their 6.2s eventually take out the pistons and rings.  Knock and ping cannot always be detected by ear, it must be measured with a scan tool as Bill mentioned.  

  • Like 2
Chevyb Enthusiast

Chevyb

Posted
Posted

have been running premium per recommendations for the engine since day 1.  runs great.  I figure if I was worried about the cost of fuel I should have bought something else.  

  • Like 4
Black02Silverado Senior Enthusiast

Black02Silverado

Posted
Posted

I'm old school and at 11.5 to 1 premium is the only way to go.  Yes the ECU can adjust but why make things work harder than they need to. 

 

Justin from Black Bear Performance highly suggest that you at least run 89.  He sees a ton of GM 5.3 and 6.2 engines come in to be tuned and like posted above, you can't always hear it but destination is there and bad ju ju.

  • Like 2
Transient Senior Enthusiast

Transient

Posted
Posted

I didn't make the truck, so I trust the professionals that did.  They recommend 93 octane, but that's not available where I'm at, so I use the next closest thing -- 91.

  • Like 2
M1ck3y Senior Enthusiast

M1ck3y

Posted
Posted
1 hour ago, eppieguy said:

I run only top tier premium fuel in mine.

 

The problem with topteir is that there's no oversight! It's an honor system. The driver dumps in whatever additives he was given before pulling out. Honor in this world 🤣

LtDan2025 Enthusiast

LtDan2025

Posted
Posted

Agreed, why would anyone spend the money on a 6.2 and then worry about the added cost of the recommended fuel?  I use 93 octane at every fill up. 

  • Like 1
Supreme Pizza Senior Enthusiast

Supreme Pizza

Posted
Posted

All I can say about octane is that you must use at least the minimum octane rating recommended by the manufacturer.

 

So why does it always say "minimum octane rating". Well, because more is OK, less is death.

 

Higher octane doesn't make a car faster, but higher octane is required by faster cars.

 

More octane = less volatile fuel.

 

You can raise your octane rating by diluting your fuel with a less volatile fuel, like kerosene.

 

High octane fuel should be cheaper than low octane fuel. But its not. Because people that need high octane fuel have more money. And because people think paying more for fuel will get you better fuel.

 

If the fuel is "too combustible", then it will ignite before the spark happens. That is called pre-ignition, spark knock, or detonation.  High compression engines have issues with pre-ignition, so they use higher octane fuel, so that the gas wont "blow up" before its supposed to during the compression cycle. Its counter-intuitive, but lower grade (deluted) fuel works better for higher compression engines. I see people put "octane booster" or "premium gas" in their crappy cars, hoping it will make them faster or more reliable. Doesn't work that way. You want to use the minimum octane fuel that is acceptable for your engine. Low octane fuel is more powerful than high octane fuel.

 

 

BLOG06_180419780_AR_0_UQSWVLQCCQFO.jpg

Z45 Senior Enthusiast

Z45

Posted
Posted (edited)

I always use 91 premium and 99% of the time its Murphy with occasional Shell and they don not have ethanol in the 91 in this area as so stated on the pumps. Near Lake Superior and no sensible boater will buy ethanol blended fuel.  On 93, a local marine dealer told me some time ago that all 93 has ethanol blend to meet the 93 level and that's why you won't find stations around here selling it.   Boaters and snowmobiler's wouldn't buy it.  Not trying to start an ethanol argument but stating reasons for only 91 available here (Lake Superior adjacent) 

Edited by elcamino
  • Like 1
RAYS B4U Enthusiast

RAYS B4U

Posted
Posted

Yes, I use premium, it's 92 octane, but it is also non-ethanol. I've been running it since 2003 when I bought my Silverado SS. Do I need it, maybe not, but whats a few penny's here and there.

redwngr Senior Enthusiast

redwngr

Posted
Posted (edited)
On 12/11/2021 at 10:00 AM, Bherm said:

How many of you are using premium fuel on the 6.2 engine 

 

Those that want to be able to make the horsepower that they paid a premium for will run high octane. 

 

Octane prevents/reduces knocking.

Engines have knock sensors.

When knock is detected the computer changes timing and fuel to avoid knock -- and this reduces available power. 

 

'Here' 'high test' is about 15% - 25% more expensive than 'regular'. 

 

fwiw, premium does NOT contain more energy. 

As posted by supreme pizza, octane makes less volatile so it burn slower, which prevents/reduces knock. 

 

I see from the picture that, similar to here, premium is 2.64/2.14 = 1.23 times the cost of regular at that location. 

 

 

Everyone gets to decide what they want to do about engine choice and fuel choice.

If there was a single right answer there would only be one engine and one fuel. 

Edited by redwngr
  • Like 1
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