Do yall use regular or mid grade gas in the 5.3?

[swathdiver]

The OP has a direct injected engine. Many years ago I challenged @Miami-Dade to run higher octane fuel in his Tahoe and he accepted the challenge and proved me wrong! My contention was that higher octane fuel delivered better fuel mileage. Well, not in a direct injected engine!

For 40 years I'd been proving in carbureted and fuel injected engines that higher octane fuel does increase efficiency, from lawn mowers, generators, Ford Fiestas, Pontiac minivans to Gen IV LS engines. Then Gary showed me that the new direct injected engines were so efficient that they didn't need or benefit from the more expensive fuel.

My father runs 89 in his turbocharged and direct-injected 2023 Kia Sorento. He said it makes more power and gets more range compared with 87.

I was running a long term test on 93 comparing different brands of fuel but paused it to run E85 since late 2024!

 

[vcode]

The OP has a direct injected engine. Many years ago I challenged @Miami-Dade to run higher octane fuel in his Tahoe and he accepted the challenge and proved me wrong! My contention was that higher octane fuel delivered better fuel mileage. Well, not in a direct injected engine!

For 40 years I'd been proving in carbureted and fuel injected engines that higher octane fuel does increase efficiency, from lawn mowers, generators, Ford Fiestas, Pontiac minivans to Gen IV LS engines. Then Gary showed me that the new direct injected engines were so efficient that they didn't need or benefit from the more expensive fuel.

My father runs 89 in his turbocharged and direct-injected 2023 Kia Sorento. He said it makes more power and gets more range compared with 87.

I was running a long term test on 93 comparing different brands of fuel but paused it to run E85 since late 2024!

As I posted before, Car and Driver tests from 2001 and 2019 showed that using premium in a vehicle made for regular made absolutely no difference. In fact it lowered the fuel economy in some cases.

 

[Marky Dissod]

The OP has a direct injected engine. Many years ago I challenged @Miami-Dade to run higher octane fuel in his Tahoe and he accepted the challenge and proved me wrong!
My contention was that higher octane fuel delivered better fuel mileage. Well, not in a direct injected engine!

For 40 years I'd been proving in carbureted and fuel injected engines that higher octane fuel does increase efficiency, from lawn mowers, generators, Ford Fiestas,
Pontiac minivans to Gen IV LS engines.
Then Gary showed me that the new direct injected engines were so efficient that they didn't need or benefit from the more expensive fuel.

That just means that the GM OE 'tune' (specifically, spark timing, AND injection timing) were written for 87 -
as usual, doesn't HURT to run 89 / 91 / 93, just that you won't get better MpG than running 87.

 

[swathdiver]

As I posted before, Car and Driver tests from 2001 and 2019 showed that using premium in a vehicle made for regular made absolutely no difference. In fact it lowered the fuel economy in some cases.

That just means that the GM OE 'tune' (specifically, spark timing, AND injection timing) were written for 87 -
as usual, doesn't HURT to run 89 / 91 / 93, just that you won't get better MpG than running 87.

I've been doing it too, since 1986. My results say otherwise, every time, in all kinds of engines, excepting direct injected engines. In every instance, the engines ran smoother, made more power and delivered better economy. Someday I'll tell the story again of how my old Buick did running on unleaded 104 octane for a week.

 

[Bronson357]

Prove that to me. Show me legit documentation that proves that.

Well can you?

 

[OR VietVet]

Well can you?

Go see lake Speed Jr. at the Speediagnostix videos. I am not making claims, one way or the other. I don't need to prove anything.

 

[Bronson357]

Just curious, no disrespect!

 

[OR VietVet]

Just curious, no disrespect!

No disrespect taken.

I also, on Lake Speed Jr. recommendations, dump a bottle of Chevron Techron Complete Fuel Injection System Cleaner in every 4th tankful.

I use Valvoline Restore & Protect 5w-30 synthetic oil and a WIX 51522, long element oil filter and change every 4 months or 4k miles, whichever is first.

The cleaner the better, in all respects.

Watch Lake Speed Jr. Speediagnostix.com videos and learn. At you tube.

 

[SpareParts]

I'll be fallowing Lake's new engine oil change schedule when i get my refreshed engine done and installed!

 

[ukemike]

We once owned a petroleum delivery company back in the 80’s. Our trucks would pick up and deliver from the chevron terminal and deliver chevron gas to both chevron flagged as well as mom/pop stations all around us in east TN.

This is basically what I was going to say. I've seen a fuel truck pull out of a fancy name brand gas station and go to a bargain brand station a few blocks down the street. You can bet I never went back to the expensive station after seeing that.

On the other hand when I lived in UT there was a chain called Sinclair. They refined their own gas and it was very poor quality. I worked for a big company that maintained a big fleet of trucks and had their own fueling station. The mechanics said that they would get terrible build up of deposits when they were using Sinclair gas, so the company switched to a different brand and that problem went away. The refinery matters more than the station brand name.

 

[DoubleDingo]

Had the Tahoe now for 5 months. 91 or 92 at each fill-up. It runs great. Maybe it was fine before, but it'll get high grade top tier as long as I own it.

Bought the 91 Cherokee in 02 with 88k. Ran 87, 89 and 91 92. It runs better, has more power and improved mileage on high grade. It runs very well now with 227k.

Basically I run high grade top tier in everything and do notice better performance and smoother operation

 

[Fless]

Top Tier info at the link below. One can search for brands there, or peruse the list.

TOP TIER™ Gasoline Brands - TOP TIER™

TOP TIER™ Gasoline Brands. All retail locations within the licensed country must meet the high standards of the TOP TIER™ program.

www.toptiergas.com

 

[mountie]

Top Tier info at the link below. One can search for brands there, or peruse the list.

TOP TIER™ Gasoline Brands - TOP TIER™

TOP TIER™ Gasoline Brands. All retail locations within the licensed country must meet the high standards of the TOP TIER™ program.

www.toptiergas.com

Come to think of it…… When I lived in California, I drove up mountain grades……. I used a better tier fuel…..
Not so much since I now drive on flat roads in Florida…….

 

[SpareParts]

This is basically what I was going to say. I've seen a fuel truck pull out of a fancy name brand gas station and go to a bargain brand station a few blocks down the street. You can bet I never went back to the expensive station after seeing that.

On the other hand when I lived in UT there was a chain called Sinclair. They refined their own gas and it was very poor quality. I worked for a big company that maintained a big fleet of trucks and had their own fueling station. The mechanics said that they would get terrible build up of deposits when they were using Sinclair gas, so the company switched to a different brand and that problem went away. The refinery matters more than the station brand name.

1 reason that happens is because the 1st station can not fit the amount that was estimated the station needs.
So when the remainder does not fit in the tank, the driver lets the dispatcher know how much fuel is remaining. The dispatcher then lets the driver know where to take the remaining fuel. Typically a non branded station.
A non branded station when buying fuel directly gets the same gas as everyone else without an additive package, making it just plan gas without an additive package.
When the delivery driver loads the fuel it becomes branded with the additive package Conoco, Exxon or what ever brand.
A non branded station could be fueled with Conoco, Exxon, Shell or whoever and all mixed together.

 

[Bronson357]

I'm really curious, top tier and hi octane are 2 completely different things, yes I prefer top tier fuel, octane unless a special for hi comp or timing requires it. The 6.2 recommends but does not require hi octane. I think the 5.3,4.8 and 6.0 don't care or specifie hi octane. Shoot most 5.3 will run e 85. I have run several different grades of fuel and hand calculations and I have 4 vehicles with 5.3, 2 flex and 2 not. They all get 17+ depending on driving style. The ly7 in the tahoe regularly gets 20 + mixed driving.

I love hearing other experiences! On another note does anyone use fuel addives and can you see a difference? I have ran a few and can't tell a difference?
From what I have read it's not necessary with top tier fuel, diesel might be a different scenario?

 

[the 18th letter]

I’m surprised I didn’t see BP on the top tier list in the link above, unless I missed it.

 

[Fless]

I’m surprised I didn’t see BP on the top tier list in the link above, unless I missed it.

You didn't miss British Petroleum on the list -- it's not there.

 

[the 18th letter]

You didn't miss British Petroleum on the list -- it's not there.

I learned today that BP is no longer top tier gas.

 

[LsHart]

Octane is the rating of a gasoline's ability to withstand high compression without detonation. If your car is designed to run on 86, run it on 86. Lower octane gas actually has more energy in it than higher octane gas does. If you have a high compression engine then running low octane can cause detonation which can cause damage. Modern engines have knock sensors and will retard the ignition if there is detonation. If you have the 5.3 run the low octane because that is the lowest octane your car can use, and it what GM recommends, if you have the 6.2 run high octane because that is the lowest octane your car can use, and it is what GM recommends.

The gas companies use the names plus and premium to trick people into buying the more expensive gas thinking that it is somehow better. It is not better. It is just different. They have the same detergents and additives. The only differences are cost resistance to compression ignition.

I also have a Honda Fit. Honda says it can run on either because it will retard the ignition a little if you fill it with 86 and advance it if run on 91. When it was new I ran it for 3 tanks on premium and 3 tanks on regular, being careful to drive it consistently on both. I averaged about 3% better mileage on the premium but the cost was about 10% higher, so I have always stuck with regular since. If I were racing it, I'd want every bit of power, so I would use premium so it would run with slightly advanced ignition timing which might add 1 or 2 hp. But it is my wife's commuter now and she never revs it over 3500 anyway, so there is zero benefit to spending more.

How do I know all of this? I'm a mechanical engineer.

If it's not tuned. 87. But the 5.3 l59 ffv will run both. If it's not tuned, ruining high octane will make it ping. Lifter rattle.

 

[Cryptothedog]

I run 85 octane. Here in Utah that is our "regular" gas. The altitude is higher here which compensates for the lower octane. I have 230k miles on my suburban. Never had a problem with 85. Of course once you get down to lower altitudes they don't even sell 85 so then I just run whatever the regular grade is.