Premium Gas on 2.7 Silverado

[Aesthetix]

using premium unleaded gas 91 on my 2.7 Silverado. should i use it or 87 with 91 im getting 16mpg

[davester]

have you considered reading your owners manual to see what gm recommends?

[Black02Silverado]

It is my understanding that any turbo/supercharged engine benefits from using a high octane fuel.  Seems to make a difference on our daughters 1.4l Chevy Cruze when we use  93 over 87. 

[ShamrockShooter]

I would pay more attention to the quality of the fuel rather than octane. Top Tier fuels have better detergents to keep your engine clean. If you are going to be towing then sure try out a tank of 91 or 93. For day to day go 87 top tier gas. https://www.toptiergas.com/

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[Mountain boy]

If the owners manual does not call for it run 87. 16 seems low unless you are pushing it.

[NeverCold]

Use what the owner's manual says.  Using higher octane than recommended is a waste of money.  

From the owner's manual:
Fuel (Gasoline - Except
L87 6.2L Engine)
Regular Unleaded Fuel
Use only Regular 87 octane — (R
+M)/2 — or higher unleaded
gasoline in your vehicle. TOP TIER
Detergent Gasoline is
recommended. Do not use gasoline
with an octane rating lower as it will
result in reduced performance and
lower fuel economy. See
Recommended Fuel (Except 6.2L
V8 Engine) 0 272 or
Recommended Fuel (6.2L
V8 Engine) 0 272.

 

And page 272:

Recommended Fuel
(Except 6.2L V8 Engine)
For diesel engine vehicles, see
“Fuel for Diesel Engines” in the
Duramax diesel supplement.
If the vehicle has a yellow fuel cap
or a yellow sticker on the fuel door,
E85 or FlexFuel can be used. If the
vehicle does not have a yellow fuel
cap or yellow sticker, do not use
gasoline with ethanol levels greater
than 15% by volume. See E85 or
FlexFuel 0 273.
Use regular unleaded gasoline
meeting ASTM specification D4814
with a posted octane rating of 87 or
higher. Do not use gasoline with a
posted octane rating of less than 87,
as this may cause engine knock and
will lower fuel economy.

[MaverickZ71]

10 hours ago, Aesthetix said:

using premium unleaded gas 91 on my 2.7 Silverado. should i use it or 87 with 91 im getting 16mpg

Use at least the minimum octane that your Owner's Manual or decal inside the fuel door calls for.  

 

If that is 87 octane, you may notice a little increase in your fuel mileage if you try mid-grade or premium.  

 

My truck (5.3L) gets 1-2 mpg better fuel mileage on a tank of mid-grade or premium than it does on regular.  Maybe because it runs a little more peppy and then I don't put my foot down so hard.

 

Seems like 16 mpg is a little low for your engine, even if that is all city miles.  Is that indicated by the Driver Info Center screen?  Some of the DIC's seem to be spot on.  Mine is always ~8% overoptimistic when I hand calculate the mpg.   

Edited October 16, 2019 by MaverickZ71

[MDSilveradoGuy]

I use 87 unless I am towing in temps over 90*, at which point I will give it 91.

 

Something seems wrong, or you are really being heavy footed with it. I have a 4x4 Double Cab with 22" wheels and get ~22 average without effort (cruise set to 75-80 on freeway) consistently across tanks - and can get 26-27 with pulse gliding at 60-65 MPH. Your MPG is lower than what I get dragging around ~4,100lb of boat.

[Sin City Trail Boss]

16mpg!? Man I'm getting 17-18 on my Trail Boss with the 5.3 and I have a heavy foot.

[Ezekiel2517]

Thata really low for an engine that's built for economy.  In getting 16-18 in town with my 6.2 max trailering 4wd

[AlaskaErik]

The only thing that higher octane gas does is resist engine knock.  It has no more energy than regular gas.  It will not make your engine peppier.  It will not increase your fuel economy.  This has been proven time and time again, and yet these urban myths persist.  If your engine is designed for 87 octane gas, using premium will do nothing other than put a bigger dent in your wallet.  Premium gas is for engines that have a higher compression ratio.  If you use top tier gas, your engine should do fine for the lifetime of the vehicle.  If you use crap gas, you'll have more carbon buildup and you may experience engine knocking.  Should that happen, try mid-grade gas.  Bottom line...premium gas will do absolutely nothing for your engine if it was designed to run on regular gas.

[batman900]

With the K2, Black Bear recommended 89 or higher for the 5.3 even on the stock tune as he was seeing timing being pulled on 87. As for the new turbo,  no idea.

[zzrsouth]

Costco 87 all the way in my L3B.  Get slightly better mileage on brand name 87 but doesnt justify the price difference.

Never noticed any knocking.

[Thomcat]

Use only Regular 87 octane — (R+M)/2 — or higher unleaded gasoline.....doesn't mean use only 87. Same advice given on my '16 Malibu 2.0T but at least they were more candid in that owner's manual, explaining that the turbos are optimized for premium but will run just fine on 87 regular, although not at optimum performance levels.

Essentially the engine will run at maximum performance using premium but will run just fine although at reduced power on regular. All modern engines  are equipped with knock sensors and the higher effective compression ratios in turbos with 87 octane higher in low end molecules will cause a knock if the spark timing is advanced too far. Run these engines on regular and when the sensor sees a knock it retards the timing to compensate resulting in less power. So the engine will run just fine with no damage on a retarded spark, just less power and performance.

 

You can play with it yourself, but the 2.0T was definitely peppier and the wallet lighter on a diet of 93.