2018 Tahoe 5.3l - Gas question

[PappaBear23]

Hey all,

Just bought my first new car ever, my 2002 Chevy Tahoe 4.8l finally bit the dust with 180K, it was so good to me and it had a nice long life!

I'm in a 2018 Chevy Tahoe 5.3L its amazing so far, I miss some little quirks from my other one, but overall its a huge upgrade!

In the owner's manual it says to use top tier gas and at least 87 octane fuel. I've already figured out what top tier fuel is but is there any real difference in running 87, 89, or 91 octane gas?

I would love to know because the difference price wise between 87 & 89 are minimal where I am and I'm wondering if I'll get better gas mileage and power running 89.

Thanks,

- Colby

 

[AZCreeker]

I only put 87 in mine.
My Suburban sucks so much gas, i'll get the cheapest I can find.
FYI here is some recent articles about how higher Octane might not be worth the increase in cost.

https://www.roadandtrack.com/car-culture/buying-maintenance/a14425998/premium-gas-fuel-benefits/

 

[swathdiver]

You will almost always get better mileage running higher octane fuel. How much so depends on where and how you drive. Low octane fuels generally do not have the detergents in them that keep your fuel system clean.

Not all brands deliver the same performance either. Start a log and run a couple tanks of each while running the same profile to get an accurate comparison. If I want to lose 2 mpg and run 93 octane, I can always count on Shell to deliver the loss! If I want to lose 4 mpg, then Cumberland Farms' fuel is happy to oblige.

In thirty years it has been my experience that it costs more to run the cheap stuff than the good stuff. Don't think in terms of price per gallon, but rather, cents per mile.

For example, would you rather pay $2.99 a gallon for regular and get 12 mpg or $3.38 a gallon for high test and get 15 mpg? In this example, it costs $.25 a mile to run the "Cheap" gas and $.22 1/2 cents a mile to run the "Expensive" gas.

You'll have to work out your own numbers. One fella here with a K2 saw no difference.

 

[cardude2000]

Just depends on if you want max HP and efficiency from the vehicle. Wont hurt the vehicle to use 87 though.

 

[swathdiver]

Just depends on if you want max HP and efficiency from the vehicle. Wont hurt the vehicle to use 87 though.

It does hurt. Most of the fuel system problems we see here are from folks feeding their motors that swill. Clogged injectors, pumps whining, carbon deposits on their valves and pistons, etc. Granted, direct injection won't have fuel cleaning their valves but that's not the point. We didn't even address the poor performance, knocking and pinging.

 

[cardude2000]

It does hurt. Most of the fuel system problems we see here are from folks feeding their motors that swill. Clogged injectors, pumps whining, carbon deposits on their valves and pistons, etc. Granted, direct injection won't have fuel cleaning their valves but that's not the point. We didn't even address the poor performance, knocking and pinging.

On a 2015+ those issues would have nothing to do with using 89 vs 91.

That has to do with using crappy off brand gas.

 

[Tahoe14]

87 octane at Exxon/Mobil vs TomThumb convience store would be a big difference. I disagree that using a top tier 87 octane would cause a problem.

 

[Shadowchaser]

i use Diablo Itune2 with straight V8 setting (AFM disabled) alway use 89 and my average 16-20 mpg's

 

[PappaBear23]

You will almost always get better mileage running higher octane fuel. How much so depends on where and how you drive. Low octane fuels generally do not have the detergents in them that keep your fuel system clean.

Not all brands deliver the same performance either. Start a log and run a couple tanks of each while running the same profile to get an accurate comparison. If I want to lose 2 mpg and run 93 octane, I can always count on Shell to deliver the loss! If I want to lose 4 mpg, then Cumberland Farms' fuel is happy to oblige.

In thirty years it has been my experience that it costs more to run the cheap stuff than the good stuff. Don't think in terms of price per gallon, but rather, cents per mile.

For example, would you rather pay $2.99 a gallon for regular and get 12 mpg or $3.38 a gallon for high test and get 15 mpg? In this example, it costs $.25 a mile to run the "Cheap" gas and $.22 1/2 cents a mile to run the "Expensive" gas.

You'll have to work out your own numbers. One fella here with a K2 saw no difference.

Thank you so much! Yes I only picked up the car two weeks ago in NY, I got back to MA where I live and filled up with Cumberland farms gas and immediately noticed the difference of mpg. I'm switching over to Phillips 66 next time I fill up, looks like they are the best around quality wise.

 

[swathdiver]

87 octane at Exxon/Mobil vs TomThumb convience store would be a big difference. I disagree that using a top tier 87 octane would cause a problem.

Try it. Try Shell's 93 and Mobil's 93 and then Chevron's 93 too.

 

[RThomasII]

2016 LTZ here... Purchased brand new with 10 miles on the odometer when I drove it off the lot. I ran 87 (Shell & Exxon) for about the 1st 6 months of ownership. Then I read on here that with the compression on the 5.3 we really should be using a higher octane gas. I stepped up to 89 and I swear my truck ran better. I then stepped up to 93 and I've been there ever since. Maybe it's the placebo effect.... I don't know.... But for me the higher octane gas seems to make a big difference in the operation of my Tahoe.

For what it's worth... It was the guys over at Black Bear that posted the stuff about compression and the 5.3. I know they are a trust source around here. YMMV.

 

[thirdcoast]

OK Pappa Bear, I also have a 2018 Tahoe that I bought new in January.

I run 89 octane exclusively in this Tahoe and ONLY run major brand fuel in my vehicles.. I generally use Exxon as there is a large facility near my home and they are very busy so no old fuel in the tank// Plus it is owned by the largest fuel distributor in my area..

I track my MPG pretty close and here is what I have been getting:

Last trip to San Antonio, 156 miles one way with an average MPG of 23.4 @ 77 MPH on cruise..

Around town with occasional short highway spurts average MPG 16.7

Last combo town & highway average MPG 20.1 at speeds between 35 & 75..

Now in full disclosure, I have a Corsa catback exhaust & a CAI on the truck and I also run my tires at 37 PSI.. BTW, these MPG's are with the AC on as it has been 95+ for a while down here in South Texas..

In my 2009 6.2L Tahoe I only run 93 octane..

Good luck and stay out of the waldomart gas stations

Thirdcoast

 

[swathdiver]

I can only best my mileage on Exxon/Mobil with a good tank of Chevron. Haven't had good fortune to get consistent fills from them yet.

The mileage you guys get with those L83 is what I was getting twelve years ago with my SV6 Montana with the 240 horse V6 motor. That particular car get better mileage the faster you went. Mileage was down to 21 @ 70 but up to almost 24 at 77 mph. It got a solid 21 mpg at 90 mph too! Miss that car.

 

[tdriver113]

Black Bear tune for 93 octane.
17 MPG around town. 22 MPG on highway driving at 70 MPH.
And that stupid AFM turned off.

THANK YOU BLACK BEAR.

 

[Greg Treantos]

Top Tier is a branding campaign. Gas stations that follow their rules get the mark. I usually go to Costco for my gas and they passed Top Tier's requirements. Here is a list of other dealers that are Top Tier branded

 

[georgebuhr]

Personally, I would recommend running the higher octane, and preferably find some with no ethanol in it. Some of the Loves gas station carry 91 with no ethanol around here, and there is a local station less than 4 blocks from my house that has 91 with no ethanol. I run that whenever I can, in whatever I can. It should give you the best mileage with the least amount of deposits. After seeing what ethanol can do to a small engine, I am not comfortable running it in a car. I will use it, but switch back to no ethanol whenever I can. I don't think it is as big an issue in a car as it is small engines, because they tend to sit much more, but other than cost, I see no benefit to having ethanol in a tank.

 

[Miami-Dade]

I only put 87 in mine.
My Suburban sucks so much gas, i'll get the cheapest I can find.
/

I would not buy the cheapest fuel I can find. I would only buy top tier fuel like Exxon-Mobil.

2016 LTZ here... Purchased brand new with 10 miles on the odometer when I drove it off the lot. I ran 87 (Shell & Exxon) for about the 1st 6 months of ownership. Then I read on here that with the compression on the 5.3 we really should be using a higher octane gas. I stepped up to 89 and I swear my truck ran better. I then stepped up to 93 and I've been there ever since. Maybe it's the placebo effect. YMMV.

It is the Placebo effect. It does not run any better. The 5.3 does not need 89 or higher for your compression ratio. That is one of the reasons why GM went to Direct Injection.

Personally, I would recommend running the higher octane, and preferably find some with no ethanol in it.

Good luck on finding no ethanol in my neck of the woods or anywhere from Key West-NYC. It is not going to happen. I wish I could find no ethanol fuel.

While I was in Virginia I visited a friend who has a 2015 Yukon with the 5.3. He drove my Tahoe on I-95 and on surface streets. He has been using 89 and said he saw zero difference in his Yukon and my 87 octane Tahoe so he going to change back to 87.

I worked for company for awhile that had several 1999-2008 Tahoe's. They all ran perfectly fine on 87 for over 200K miles. No clogged injectors,no carbon deposits on valves and pistons. We did use Top Tier fuel and all vehicles were serviced regularly.

If I have any issues running 87 in my Tahoe I will let everyone here know.

So far I have not heard of anyone complaining of carbon buildup [or performance issues] on their 2015 plus 5.3 or 6.2 Direct Injection engines. Even ones with over 150K miles.

I can not believe how many people are brain washed into thinking 89 or higher octane is better for their 5.3 vehicles. I am sure the oil companies love that.

All that is just IMHO. To each their own.

 

[swathdiver]

Good luck on finding no ethanol in my neck of the woods or anywhere from Key West-NYC. It is not going to happen. I wish I could find no ethanol fuel.

Many Racetrac stations sell Ethanol free fuel Gary. Also, along US27, between Palmdale and Haines City are a bunch of stations that sell 93 octane free of ethanol. Most only sell 89 or 90 octane like Racetrac, which is right up your alley anyway! But, neither of us frequent Bloody 27 though we do go to Davenport/Haines City once every year or so.

I remember when ethanol laced fuel was mandated that my other cars lost about 2 mpg. The only benefit to us, the consumer, is that it helps prevent detonation.

 

[Tahoe14]

Try WaWa in central Florida as they have Ethanol free.

 

[Miami-Dade]

Many Racetrac stations sell Ethanol free fuel Gary. Also, along US27, between Palmdale and Haines City are a bunch of stations that sell 93 octane free of ethanol. Most only sell 89 or 90 octane like Racetrac, which is right up your alley anyway! But, neither of us frequent Bloody 27 though we do go to Davenport/Haines City once every year or so.

I remember when ethanol laced fuel was mandated that my other cars lost about 2 mpg. The only benefit to us, the consumer, is that it helps prevent detonation.

Try WaWa in central Florida as they have Ethanol free.

Thanks for info guys!!

When ethanol first came out I had 4.6 V8 Town Car. I lost about 2 mpg just like you said immediately. I hear you on Bloody 27. Bloody 27 and Krome are the worst.

I will not buy RaceTrac fuel as a friend got a tankful of dirt in his Mercedes a couple of years ago at a RaceTrac in Broward County off I-95. This station is a super busy station 24/7. 1500 bucks later [dealer serviced] it was running good again after it was towed in.

When I go thru Central Florida Gary I barely get off I-95. But good to know.