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87 vs 89 vs 93 (again)

Jack.

Jack.

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I been doing quite a bit of research into this ever since I got the truck and seeing how I fuel up at Costco I usually just go for premium. The other day we got hit with the Blizzard and I really needed gas so I stopped by a station locally (costco was closed) and their premium pump wasn't working nor was the mid grade pump for some reason... but the regular one did so I just filled up with regular.

I noticed that the engine runs a bit quieter with 87 recently and honestly I think the fuel economy increased a little too. Could be placebo lol.

For all those who ran premium and switch to midgrade/regular or vice versa, have you guys notice any different within your truck performance base on your grade of gas?
 
Jack. said:
I been doing quite a bit of research into this ever since I got the truck and seeing how I fuel up at Costco I usually just go for premium. The other day we got hit with the Blizzard and I really needed gas so I stopped by a station locally (costco was closed) and their premium pump wasn't working nor was the mid grade pump for some reason... but the regular one did so I just filled up with regular.

I noticed that the engine runs a bit quieter with 87 recently and honestly I think the fuel economy increased a little too. Could be placebo lol.

For all those who ran premium and switch to midgrade/regular or vice versa, have you guys notice any different within your truck performance base on your grade of gas?
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Just due to the differences in how octanes work, I can see how there may be a slight increase in fuel mileage going from premium to regular. The adaptives in the PCM have adjusted to the higher octane with spark and fuel trims. Lower octane doesn't need as much spark, and once the PCM adjust to the lower octane your mileage will adjust as well.

You honestly need to run a minimum of three full tanks at the lower octane to document any differences. There are a lot of variables, even outside PCM adaptives, that will effect it
 
I think there’s a lot of strong opinions out there, but the general consensus seems to be that 87 is fine if you don’t tow heavy or drive with a lead foot. I personally use premium but I’m guessing the majority of these trucks on the road are sipping regular gas for thousands of miles with no issues.
I ran regular for the first 8,000 miles and the things I noticed from switching was MDS stays on way longer ( because the higher grade fuel can advance timing more ) as for mileage mine didn’t change much, maybe .5mpg better, not enough to justify the change on that alone.
I’ve averaged 17.5 over the past 37k miles.
 
Since you said "engine runs more quietly on 87" I'm going to suggest that yes it's just placebo. If anything, you should be getting same or higher mpg on 89+ and there would be no difference in noise unless you're referring to engine knock in which case 89+ would be better to reduce noise.

It really depends on the engine so it's not a golden rule; but for our hemis, they definitely run better on 89/91 and this is backed up by guys who have done data logging while trying different octanes.
 
After two tankfuls of 93 Costco I notice .7 to 1 mpg better. When I am at half tank I will top off with 87 then switch back to 87 and see if there is a difference?
 
silver billet said:
Since you said "engine runs more quietly on 87" I'm going to suggest that yes it's just placebo. If anything, you should be getting same or higher mpg on 89+ and there would be no difference in noise unless you're referring to engine knock in which case 89+ would be better to reduce noise.

It really depends on the engine so it's not a golden rule; but for our hemis, they definitely run better on 89/91 and this is backed up by guys who have done data logging while trying different octanes.
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Sorry I didn't mean engine, more or so the way my borla is sounding. It's a bit more quieter with the 87 haha.
 
I stick with the 87 unless I plan on going tow something like my camper. Then I will switch it up to the midgrade a tank or two ahead of time. Haven't noticed any difference then again my daily commute is 2 miles through town.
 
Bought in April 2021, I ran 87/92 every other tank for about 6 months. Then 92 price went down and have been filling only premium the last 3-4 months. Truck runs better, not much difference in mileage, but I think that’s my foot’s fault. 🤦🏻‍♂️
Price of 92 has gone up at Sam’s again, but I doubt I will go back to swapping grades.
With my 44 mile daily drive up and down and through the mountain, I have experienced much better response, better pickup, running just premium. The savings isn’t worth it, at least for me.
Dropping the foot to go around slow moving traffic on an incline is a lot funner on good gas! 👍😁
 
I honestly don't notice a difference. With the price difference between 87 and 89 going up in my area, I tend to stick with 87 now. When the difference was 10 to 15 cents between them, it was a no brainer to go with 89. Now that it's 20 to 30 cents per gallon, and more, I'll just stick with 87. Not something that's going to break the bank, but every little bit adds up. And with the inflation we're seeing right now that little bit is more important than it was a year ago.
 
E15 around me cost more than 87 now. It use to be cheaper but not any more. 89 use to be about .15 or so more but now it is double that.
 
397STROKER said:
E15 around me cost more than 87 now. It use to be cheaper but not any more. 89 use to be about .15 or so more but now it is double that.
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Hawaii lifted the ethanol requirement a few years ago, but we still run E10 at majority of the stations. Sam’s and Costco are at least a .25-.35 cent difference than the average of other stations, depending on where you fill. Ethanol free will cost at least .75 to $1 more, where available.
I work on a military base, and gas prices are high there, too.
That being said, a full tank of 92 from Sam’s will currently run me around 130.00. I try to fill at a half or around there. However, last week I had under an 8th, and it costed 116.00 to fill er up. Ouch.
 
MontFla said:
After two tankfuls of 93 Costco I notice .7 to 1 mpg better. When I am at half tank I will top off with 87 then switch back to 87 and see if there is a difference?
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Does Costco fuel contain additives? When my son was having issues with his GMC a trusted mechanic asked him what brand gas he used, which was Kroger. The mechanic told me stations like Kroger, Sams, Costco and the like buy fuel without all the additives therefore that's why it's cheaper.

Of course this came from a mechanic associated with a BP dealership so this may be fake news but I do trust the guy and when my son filled up with BP gas the problem went away. And I'm not a fuel expert so I don't even know what additives he was talking about!!
 
There is merit to that. Tuners and mechanics will usually say to try and run “top tier” fuel for best performance and less issues.


Sent from my iPhone using Tapatalk
 
GeorgiaBoy said:
Does Costco fuel contain additives? When my son was having issues with his GMC a trusted mechanic asked him what brand gas he used, which was Kroger. The mechanic told me stations like Kroger, Sams, Costco and the like buy fuel without all the additives therefore that's why it's cheaper.

Of course this came from a mechanic associated with a BP dealership so this may be fake news but I do trust the guy and when my son filled up with BP gas the problem went away. And I'm not a fuel expert so I don't even know what additives he was talking about!!
Click to expand...
Costco gas is a "Top Tier" gas, so yes, they add additives. I've read elsewhere that they purchase additive-free fuel but they add their specific additive on-site.
 
GKIII said:
Costco gas is a "Top Tier" gas, so yes, they add additives. I've read elsewhere that they purchase additive-free fuel but they add their specific additive on-site.
Click to expand...
Good to know! There is one right around the corner. Thanks
 
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