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

[Tahoe guy]

I have always used regular in my 2018 but on a road trip last week I had an empty tank and put mid grade and got alot better gas mileage.

Outside of that are there any other benefits or is it a waste of money?

fwiw I'm strictly a chevron guy and use the app/card for discounts.

 

[Joseph Garcia]

I don't know if you really pick up anything there. The tune on the motor is set for 87 octane. But sometimes, it just feels better to run a higher octane grade in your vehicle. For example, in my Honda Fit, it calls for 87, but I've used 89 ever since I owned it. Does it make a difference, I have no idea. But, I feel better about doing that.

 

[ukemike]

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.

 

[Miami-Dade]

Since I bought my 5.3 Tahoe brand new in 2016 I have put in only 87 regular. I been doing that for 203K miles. Use Exxon-Mobil 99.9% of the time. One time awhile back I put in 93 octane [the pumps were labeled backwards in South Carolina] and I saw no improvement in gas mileage or performance. To each their own.

 

[Rygrego]

I took a work trip to Philadelphia from California. I ran premium all the way there because the way they reimbursed me was to double my cost coming out. On the way home I ran regular and got no difference in mileage at all , also made a little extra money. If a vehicle doesn't "require" premium you're wasting money.

 

[ReaperHWK]

Agree. For a 5.3 use regular.

 

[OR VietVet]

I run the Chevron Mid grade in everything. More additives for cleaner fuel system. I also add Chevron Techron Complete Fuel System Cleaner about every 4th tankful. It was recommended to me by Lake Speed Junior. He recommends keeping the fuel system as clean as you can. Top tier fuels have more additives to help with the cleaning. Bottom tier fuels, like at Jake's Gas Stop, are less expensive for a reason.

 

[89Suburban]

I run 89

 

[Marky Dissod]

Three reasons to use 91 or 93 even when OE recommendation is 87:
1. Towing / hauling heavy (or racing), in which case you're paying for additional insurance against detonation which can't hurt even if it doesn't help
2. PCM / ECM has been tuned specifically for 91 or 93 octane, in which case OE recommendation (and this thread) no longer applies
3. You're the 1st owner of a brand new engine you're breaking in, you happen to know that 91 / 93 TopTier gasolines also have extra upper cylinder lubricant,
and you plan to own it forever (can't speak for lesser gasoline 'brands')

I nearly always run 87, unless I find 89 or 91 or 93 at an unusually low price compared to 87, then I switch to Tow/Haul mode
(which I had tuned to act like Performance mode), and indulge my leadfoot with more glee til I go back to the usual 87 and drive more like a wuss again.

 

[k_arnold72]

Three reasons to use 91 or 93 even when OE recommendation is 87:
1. Towing / hauling heavy (or racing), in which case you're paying for additional insurance against detonation which can't hurt even if it doesn't help
2. PCM / ECM has been tuned specifically for 91 or 93 octane, in which case OE recommendation (and this thread) no longer applies
3. You're the 1st owner of a brand new engine you're breaking in, you happen to know that 91 / 93 TopTier gasolines also have extra upper cylinder lubricant,
and you plan to own it forever (can't speak for lesser gasoline 'brands')

I nearly always run 87, unless I find 89 or 91 or 93 at an unusually low price compared to 87, then I switch to Tow/Haul mode
(which I had tuned to act like Performance mode), and indulge my leadfoot with more glee til I go back to the usual 87 and drive more like a wuss again.

Where does one go to get their tow mode tuned for performance?

 

[RST Dana]

I run the Chevron Mid grade in everything. More additives for cleaner fuel system. I also add Chevron Techron Complete Fuel System Cleaner about every 4th tankful. It was recommended to me by Lake Speed Junior. He recommends keeping the fuel system as clean as you can. Top tier fuels have more additives to help with the cleaning. Bottom tier fuels, like at Jake's Gas Stop, are less expensive for a reason.

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.

 

[Marky Dissod]

I went to pcmperformance.com, it's in my sig. My considerable experience tuning Ironblock LT1s makes me an unusually educated consumer,
so I was persnickety about things I wanted and how I wanted them (just one example: my Hot mode is enabled @ 230F instead of 257F, stuff like that).

In most of NY / NJ / CT / PA, 91 / 93 octane costs WAY too much more than 87, so I got tuned for 87,
but whenever I find better-than-reasonably priced 89 / 91 / 93 petrol I 'waste' money on it because the upper cylinder lubricants and detergents are worth it TO ME.

 

[OR VietVet]

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.

I am assuming that you are proposing that there was only one tank on that truck and that you are saying that the additives used today are the same as the 80's.

 

[k_arnold72]

I'm in MD so I'm all too familiar with the prices, I was hoping to get an e85 tune from someone locally. I'll look them up. Thank you

I went to pcmperformance.com, it's in my sig. My considerable experience tuning Ironblock LT1s makes me an unusually educated consumer,
so I was persnickety about things I wanted and how I wanted them (just one example: my Hot mode is enabled @ 230F instead of 257F, stuff like that).

In most of NY / NJ / CT / PA, 91 / 93 octane costs WAY too much more than 87, so I got tuned for 87,
but whenever I find better-than-reasonably priced 89 / 91 / 93 petrol I 'waste' money on it because the upper cylinder lubricants and detergents are worth it TO ME.

 

[RST Dana]

I am assuming that you are proposing that there was only one tank on that truck and that you are saying that the additives used today are the same as the 80's.

Each fuel tanker has anywhere from 4 to 6 separate compartments all for individual products.
Additives may be different, but not $.50 per gallon different.

 

[tom3]

When I saw the 11 : 1 compression ratio in this 5.3 I decided to never put low octane fuel in it. BP midgrade or Sam's Club premium only. But in over 6 years driving it has 36k miles today so it's not a big cost factor. I do mostly loaded up highway higher speed driving and get super mpg I think. Recent:

 

[OR VietVet]

Each fuel tanker has anywhere from 4 to 6 separate compartments all for individual products.
Additives may be different, but not $.50 per gallon different.

Even here on the west coast, I am in Oregon, I do not see $.50 per gallon difference, anywhere. Most I have ever seen is $.20 a gallon. I do know that the diesel can be quite a bit more expensive here.

Where are you seeing $.50 difference per gallon?

 

[West 1]

I think what needs to be added here is the move to Direct Injected fuel injection, was that 2016? Direct injected engines spray fuel into the combustion chamber at 800-3600 PSI when the piston is at Top Dead Center. This super high pressure fuel spray cools the chamber and eliminates detonation. For this reason 11 to 1 compression is no longer a detonation issue. Earlier engines use standard injection running 40-100 PSI that is sucked into the intake ports just like older carburetors did. In early engines/non direct injection models the fuel is mixed with the air intake and compressed by the piston on the compression stroke. Fuel is in the cylinder for the entire compression stroke.

Sometimes due to many issues if the tune is not perfect this fuel charge could light off early before the piston was at top dead center and before the spark plug ignites. This is detonation or early fire in the hole. Detonation robs power and can break parts, rings, pistons, head gaskets, spark plugs. IT is very bad for engine health.

Direct injection eliminates detonation and is a huge step forward. There is no fuel in the cylinder till it is time for it to fire. This allows for more power, better mpg and cleaner exhaust emissions.

What I fail to understand is why some direct injected engines, including my Porsche require Premium Fuel today. I do understand that premium burns more predicable than regular fuel but with no detonation worry is it really necessary in a direct injected engine?

 

[tom3]

I suspect it's because of the minute quantity of fuel being injected. A slower burn rate would maybe give a broader combustion distribution across the piston. These engines do give some pretty amazing performance.

 

[mountie]

The one time I spent more money for fuel…. Years ago ( 1986) I had a 1965 Porsche SC…..
On longer trips I filled it with Av-gas….. Oh, my….. what difference !!

I am fine using regular in my ’05. I felt no improvement with mid-grade gas.