Should I run 87 or 89 fuel in my 2017 Silverado 1500 5.3L?

Donstar · July 4, 2017

A stock OEM motor should never knock on any level of fuel 87+. The knock sensor is there so if u run some super shitty watered down gas and there are problems.

If you go to any Shell or Mobil you will be fine. The difference in octane between 87 and 89 is so obsolete it isn't even funny. So to the people that say they see a drastic difference is total bullshit.

I run race cars on all levels of gas. Now 93 vs 87 will have some difference but minimal. Real difference is E85, have an ecu tune for that and it's octane level is rated at 105, but you have to dump 20pct more. But it runs cooler and you can make bigger power.

So drop the bullshit between 87 vs 89.....

Members have written in with their opinions and observations. They have been respectful and interesting to read. Calling it "bullshit" proves that you are more knowledgeable than us and you will undoubtedly garner support for your tough stance on this topic! Too bad you find it necessary to criticize in this manner.

LyleLukas11 · July 5, 2017

Members have written in with their opinions and observations. They have been respectful and interesting to read. Calling it "bullshit" proves that you are more knowledgeable than us and you will undoubtedly garner support for your tough stance on this topic! Too bad you find it necessary to criticize in this manner.

I apologize if you took it that way, but I see it as people are lying to make themselves better and better then others and THAT I do not like nor condone. This is my reasoning for the stronger stance. I honestly didn't think "bullshit" was that horrendous of a word either. I guess it comes across more stern online because I am pretty light hearted guy.

Silverado Steve · July 5, 2017

At the end of the day who cares what orhers choose to put in their tanks...have money to blow put in premium. Paycheck to paycheck put in 87....do what your wallet can handle.

Grumpy Bear · July 5, 2017

Running a Scan Gauge II or Live Tune in real time. 87 gas of any supplier, top tier or otherwise, will ring the Knock Retard bell now an again on a hill or in some heat. Then again so will 93 non-alky gas. Been there. Done that. Burned the Tee Shirt. Don't guess at what can be measured.

The question I ask myself is two fold. Can I measure a difference that is statistically significant over a protracted length of time. Meaning more than a tank or two's combine average. And two, is any significant difference in mileage MEASURED in proportion to the gas cost off set. That is; If it cost 20% more it better deliver 20% PLUS more mileage. The Knock sensor is there to 1.) provide the maximum effective timing 2.) protect and serve. It can be in knock retard 10 degrees until the cows come home and not hurt the motor.

As this is never the case locally (priced vs gain) I don't even have to test it. It's the reason E85 never enters my tank. Even when it's 20 percent cheaper it still cuts mileage nearly in half. That's an easy figure. What you can measure, in states were it is available, is the difference between no alcohol 87 and E10 or E15 fuels. Then justify by the fuel cost. It rarely does. Lobby $$$$ at work there.

Donstar · July 5, 2017

Running a Scan Gauge II or Live Tune in real time. 87 gas of any supplier, top tier or otherwise, will ring the Knock Retard bell now an again on a hill or in some heat. Then again so will 93 non-alky gas. Been there. Done that. Burned the Tee Shirt. Don't guess at what can be measured.

The question I ask myself is two fold. Can I measure a difference that is statistically significant over a protracted length of time. Meaning more than a tank or two's combine average. And two, is any significant difference in mileage MEASURED in proportion to the gas cost off set. That is; If it cost 20% more it better deliver 20% PLUS more mileage. The Knock sensor is there to 1.) provide the maximum effective timing 2.) protect and serve. It can be in knock retard 10 degrees until the cows come home and not hurt the motor.

As this is never the case locally (priced vs gain) I don't even have to test it. It's the reason E85 never enters my tank. Even when it's 20 percent cheaper it still cuts mileage nearly in half. That's an easy figure. What you can measure, in states were it is available, is the difference between no alcohol 87 and E10 or E15 fuels. Then justify by the fuel cost. It rarely does. Lobby $$$$ at work there.

Well stated argument. When the "engine retard bell is rung" it may not hurt the engine however does this not reduce power, albeit negligible? It is very difficult to shake the idea that paying a little more for a little higher octane is not somehow good for our truck. It is not unusual to pay extra for products that we believe are better but statistically demonstrate no noticeable improvements whether it be for our vehicles, homes, personal appearance or hobbies.

Grumpy Bear · July 5, 2017

Well stated argument. When the "engine retard bell is rung" it may not hurt the engine however does this not reduce power, albeit negligible? It is very difficult to shake the idea that paying a little more for a little higher octane is not somehow good for our truck. It is not unusual to pay extra for products that we believe are better but statistically demonstrate no noticeable improvements whether it be for our vehicles, homes, personal appearance or hobbies.

Who could argue and win such an exchange? Most certainly! We do this very thing all the time. Fact is, this exact human nature is the heart and soul of marketing. They rely on this nonsensical behavior to override facts in the face of contradictory scientific evidence. Because these lies are indeed partly true we believe them whole heartedly enough to argue heatedly, personally and often hurtfully.

Detonation is more than compression ratio and inlet valve closing angles commanding, in part, cylinder pressures. It’s also about ‘end gas’ residual makeup and percentage on the succeeding inlet stroke. Products of overlap dwell and throttle angles command over MAP. It's about piston diameter and flame speed. It is complicated and has been talked about for decades as if it were as simple as icing a cake. It is not. It’s chemistry and it is FULLY dynamic.

Base timing is relatively easy if you have a dyno and strict control over fuel composition and quality. Nail down the highest timing that produces highest power (if that is indeed your goal) for every point in the rpm band. It takes allot of pulls to get close though. Even then there are countless variables off the dyno. You can’t control the weather or elevation. Problem is, your motor runs that scenario less than 1% of its operating life. The rest are millions, no countless iterations of conditions that exact their own unique timing value. Sadly there is enough variation in fuel from day to day to make nailing that down perfectly impossible. Pre computer this tuning thing was an exercise in compromise always leaving something on the table. Not because you couldn’t get close enough. Because not leaving some safety net meant holes in a piston, banged bearings or burnt valves were darn near assured.

Today we have learning computers with 'ears' operating it pretty much to perfection. Fact is, if you are not experiencing some degree of knock retard your leaving power on the table.

Can you measure it? If you can is it enough to be useful? If it’s useful is it cost effective?

I have a confession to make. I’ve bought more than my fair share of ‘snake oil’. Hang your head and stamp your feet in disgust if you must but as I am not the brightest bulb in the box as I often refused to listen to the evidence, or did to bad opinion as the case may be.

Now I buy fully aware that I’m likely to be ‘had’. ONCE. No worries. I put it to the test and measure and let the data instead of opinions have the final say.

Here’s a thought you can take or leave as you wish. Mechanical compression ratio has only the effect on cylinder pressure the inlet valve closing angle permits. ‘Back in the day’ we use to have a rule of thumb that said one point of compression is equal to ten points of octane. Boy is that so last year. 87 octane being run in 10:1 + mechanical compression ratio motors is nothing short of a miracle of technology.

AskMeAboutMySilverado · July 10, 2017

I have a 5.3L Silverado (2016) with 14000 miles. I did some testing of my own:

On summer fuel (non-top tier gas)

87 Octane - 18.7 mpg over 400 miles driving (half city 30 mph, half highway 65 mph)

91 Octane - 19.0 mpg over 400 miles driving (half city 30 mph, half highway 65 mph)

87 Octane from Shell Station (top tier) - 20.0 mpg over 400 miles driving (half city 30 mph, half highway 65 mph)

all the same route driving. filled up at almost completely empty. Put 25ish gallons in (only a 26 gallon tank, so damn near empty)

Conclusion: Better off buying Shell or good top tier gas at 87 Octane than cheaper station's 91 or 93.

winn0040 · July 10, 2017

I have a 5.3L Silverado (2016) with 14000 miles. I did some testing of my own:

On summer fuel (non-top tier gas)

87 Octane - 18.7 mpg over 400 miles driving (half city 30 mph, half highway 65 mph)

91 Octane - 19.0 mpg over 400 miles driving (half city 30 mph, half highway 65 mph)

87 Octane from Shell Station (top tier) - 20.0 mpg over 400 miles driving (half city 30 mph, half highway 65 mph)

all the same route driving. filled up at almost completely empty. Put 25ish gallons in (only a 26 gallon tank, so damn near empty)

Conclusion: Better off buying Shell or good top tier gas at 87 Octane than cheaper station's 91 or 93.

Since Shell has started participating with Hyvee (a local grocery store) on their fuel rewards program I've started filling my tank with their fuel as well and my last three tanks of 87 have been 1-2mpg better than what I had been seeing previously using other branded fuel. Take it for what it's worth, but I'm on board with this. I set my all time record in 35,000 miles on the DIC 400 mile calculator with 23.1 where it had previously shown 21.7mpg. My DIC seems to read between .5 and 1 whole mpg generous, however.

Greg15z71 · July 10, 2017

I run 93 all the time, dunno if it helps but it's like 7.00$ more per tank to run better gas

sage55 · July 10, 2017

I keep seeing people talking about "top-tier" fuel? What the heck is that and how do I know what fuel gas stations use?

I don't have a favorite gas station that I go out of my way to buy gas from. I usually drive the truck until it's getting close to empty and the next available gas station is the one I pull into. Sometimes I might fill up at Costco if I'm on that side of town.

But I don't recall any of the stations saying "Hey look we have X brand gas!".

Brian S. · July 10, 2017

Does it matter if I run 87 or 89 in my truck? Better mpg? Anything?

Sent from my iPhone using Tapatalk

Have never noticed a difference using fuel other than E85.

Ozer · July 11, 2017

I keep seeing people talking about "top-tier" fuel? What the heck is that and how do I know what fuel gas stations use?

I don't have a favorite gas station that I go out of my way to buy gas from. I usually drive the truck until it's getting close to empty and the next available gas station is the one I pull into. Sometimes I might fill up at Costco if I'm on that side of town.

But I don't recall any of the stations saying "Hey look we have X brand gas!".

On that note, i used to work at a privately owned Mobil station and we used to get gas delivered from Gretty (i think) and the driver then used to go next door to Hess and fill them up as well. So i dont know if it was Mobil quality gas or just whatever. I guess unless you go to an authorized real brand gas station, you may not know.

Brian S. · July 11, 2017

At the end of the day who cares what orhers choose to put in their tanks...have money to blow put in premium. Paycheck to paycheck put in 87....do what your wallet can handle.

That's one theory, but the OP asked if there was a difference in mpg or performance in an engine designed for regular fuel.

Road and Track magazine says this based on scientific research done on the subject:

http://www.roadandtrack.com/about/a31295/high-octane/

"What AAA found out was that premium gasoline in a car designed for regular didn't produce better fuel economy, reduce pollution, or make your car go faster—in short, all it did was take a bit more of your money."

OP:

87 and 89 octane fuels are all 10% ethanol blends in my experience. The octane difference is too small to allow for the performance difference Gen V engines get from 105 octane E85, and engine knock is automatically adjusted for. (and again, this is a tiny difference in octane)

If you run 91-93 octane no ethanol gas you'll get a little better mpg, but probably not enough to justify the cost difference.

Your truck won't be ashamed if you use the cheaper gas, even if you're rich.

Donstar · July 11, 2017

I keep seeing people talking about "top-tier" fuel? What the heck is that and how do I know what fuel gas stations use?

I don't have a favorite gas station that I go out of my way to buy gas from. I usually drive the truck until it's getting close to empty and the next available gas station is the one I pull into. Sometimes I might fill up at Costco if I'm on that side of town.

But I don't recall any of the stations saying "Hey look we have X brand gas!".

Top Tier gas is recommended in your owner's manual. It is a designation many popular gas stations have and you will find lists online. Costco sells Top Tier gas.

ChevyRoofer · July 11, 2017

Top Tier gas is recommended in your owner's manual. It is a designation many popular gas stations have and you will find lists online. Costco sells Top Tier gas.

I keep seeing people talking about "top-tier" fuel? What the heck is that and how do I know what fuel gas stations use?

I don't have a favorite gas station that I go out of my way to buy gas from. I usually drive the truck until it's getting close to empty and the next available gas station is the one I pull into. Sometimes I might fill up at Costco if I'm on that side of town.

But I don't recall any of the stations saying "Hey look we have X brand gas!".

Gas card for work here and I only use mid-grade. If I had the 6.2, I would only use premium. Why? Engine compression rates differ.

http://www.gm-trucks.com/forums/topic/187596-top-tier-gas/