93 octane gas isn't the same at every gas station

[broku518]

Well, I filled up recently at some local pump, no major brand. Couple days later I noticed the car is running funky - harder to start, extra smoke, the smell is different.

Did some googling and see that 93 octane isn't same across the board. Go figure!
As a precaution I will be only getting my gas from major gas stations - Exxon, Shell or BP.

[GoDadGo]

Great Advice So Thanks For Sharing This Information!

[JIMOCO]

Google top tier or tier one gas. You will find some interesting articles about the quality of gas and the brands offering a better product. After reading this I have been avoiding any off brand gas. Maybe the octane rating will be more accurate as well.

[michael everson]

I don't know about where you live, but around here they all get it from the same terminal.
Mike

[canuck1]

Where I live, I avoid buying from the low (sales) volume stations since I don't know how often the storage tank is re-filled. At a small, lower use station, the premium gas that was delivered last year might still be in the storage tank the pump draws from! I don't think this helps when it comes to overall fuel quality.

Sean

[JIMOCO]

I agree Mike. The AAA article notes the gas is often stored in common containers with the additives being added after the retailer purchases it. The studies noted suggest purchasing from a tier one or top tier supplier is worth the additional cost. From my vantage point why choose a brand that has not made the list. It could be better but it won't be worse.

[BEAR-AvHistory]

Yeah the gas comes out of the same terminals in a lot of places but the additive packages the truck driver dump in the trailer are custom to the brand they are delivering.

[Gumball]

Another thing to watch out for is if the tanker is still at the station, always ask the driver if he is about to fill the storage tanks or if he just finished. If he just finished, head on down the road, as the filling can stir sediment in the storage tanks and get into your car. Not a major problem - and you never know when the tanker just left before you arrived - but better to avoid the risk of getting dirty fuel.

[turbomacncheese]

My buddy used to work for AZ State and got to audit gas stations for gas records and taxes. He's got some stories.....

[frd2]

I work for one of the “majors”. We have refineries in locations without gas stations and we have stations in areas with none of our refineries. We trade gas with everyone. My refinery gasoline may be in any major station and also across the road in a 7 eleven. 93 is 93 other than whether it has ethanol. Only difference is additives and they matter 20000 miles later not that tank. Only thing more a commodity to a set standard is Diet Coke.

[mikeinatlanta]

I have started measuring ethanol content and believe this is part of the issue. Have found up to 20% in a pump not labeled as such. Also found a gas station selling counterfeit Sunoco race gas at the pump (Peachtree City Ga). The fuels may come from the same refinery, but that in no way corelates to what the gas station owner is doing to rip you off.

Recent cross country trip in my new F150. The new Fords can tell how much ethanol is in the fuel and will reduce miles remaining in the tank accordingly. A full tank of E10 is good for about 650 miles. Within five miles of filling with what was supposed to be E-10 my miles remaining had dropped over 100 miles. Based on running E85, I'm guessing it had at least 25% ethanol. I have found that the miles remaining about ten miles after fill up to be a very good indicator of gas quality, and top tier definitely makes a measurable difference.

[mike223]

I have started measuring ethanol content and believe this is part of the issue.

Good to know.


The second biggest variable is probably butane content.

Maybe 2% in summer blends, 10%+ in winter blends.


10% won't live long in summer temperatures (it escapes as a vapor)...

[Jsf74]

1st question is why run 93? Most street cars actually loose power on premium.

[GoDadGo]

1st question is why run 93? Most street cars actually loose power on premium.

It all depends on your engine type, compression and combination.


EXAMPLE:

Ford' Coyote is a dynamic VVT engine, while my set up is old school static push-rod motor with a pretty high compression for having iron heads. I'd have to run my timing way down if I wanted to run 87 Go-Go-Juice over the more expensive 93 octane. This would probably kill 50-100 horse power and ruin throttle response and drive-ability.

Hope This Helps!

[broku518]

Thanks for your feedback. I am not much of a gearhead, just a normal dude here.

I noticed this change in behavior in my car and simply traced down to single variable - it was different fuel. I could have started tweaking and taking stuff apart, but called Mike F. (he built my DART engine) chatted couple minutes and was at ease.

Thanks,
Broku518

[BEAR-AvHistory]

1st question is why run 93? Most street cars actually loose power on premium.

Don't agree with your claim but will not go there as it gets into what I call the Octane Wars.

FORD lists the COYOTE advertised horsepower with an * attached. The * reads engine power rating based on 93 octane. Lower grade fuel will lower power.

It must suck to live in states with 91 premium instead of 93 like we have in most of the east coast.

[NAZ]

93 octane? Best we have here is 91 which is OK at Flagstaff's 8000' plus density altitude but no way I could run that with my SBC 11.7:1 CR at sea level. When I run at PHX (1145' ASL) I mix VP110 at $86 a 5-gal pail to keep the engine happy at that higher atmospheric pressure. Consider yourselves lucky with any 93 octane. And if I could get E85 at the pump I'd be in racer nirvana.

[KenWilkinson]

My buddy used to work for AZ State and got to audit gas stations for gas records and taxes. He's got some stories.....

Hey! You can't tease us like this! Get your buddy online and typing.

[GoDadGo]

93 is the common grade for Premium with or without Ethanol in my home town so I'm feeling blessed.
Heck 100-LL is only $5.00 per gallon as long as you tell the fellows that it is for your Air Boat.
You just need to run it at 100-1 Marvel or TCW-3 to keep from washing the cylinders.
I guess since we produce and refine so much of the stuff that it is easy to get.

[turbomacncheese]

Don't agree with your claim but will not go there as it gets into what I call the Octane Wars.

I don't know that I would go as far as "most" cars, either, but I DO know that the guy who coached me on my first engine build...well, the first one that didn't need to be rebuilt under 1000 miles - so, my SECOND engine build...had been building and racing motors for nearly 30 years at that point, and told me they used to run the cheap stuff, pull the timing, and pick up some precious fractions of a second on the ET. It was already early 2000s, and he was reminiscing about the good old days, soooooo, I'm willing to be that a lot of it has to do with engine technology and how some of the old-man-wisdom refuses to die.

Hey! You can't tease us like this! Get your buddy online and typing.

Well, the first thing that comes to mind is all the native reservations out here. He told me the pipelines carry all sorts of petroleum, not just gasoline. So a pipe might run gas one day, oil the next, kerosene the day after that. They are supposed to run a certain amount of product through when making the changes, and that mixture isn't supposed to be sold with either product. But since the reservations aren't under US jurisdiction, they'd dump it in the tank anyway and sorry for your luck if your truck doesn't run well anymore. I'll ask him for the most outrageous thing he saw, see what he gives me. A lot of the stories were about tax evasion, maybe less interesting here.

[TexasAviator]

I built my engine so I know every nook and cranny of the compression. I am running 11.4:1 and 91 octane at 1700 ft above sea level. The engines cam matters more than anything. My compression is high but my cam bleeds off enough to keep 180 cranking psi. I am very happy and love the power my little 347 made (475hp).

Now with the Coyote, the electronics package is so sensitive it can detect knock. If you run crap fuel in a Coyote it will lose power. Run 93 and the car will add timing for power. Could be as much as 10hp per octane full number. Not points, becareful when something says a full point. It means .1 in octane.

[BEAR-AvHistory]

I can get 100 at the local pump but run 93 as the car is specifically tuned for it. Used to run 100 & mixes of 100/93 when I was driving a modified twin turbo BMW 335is. Was $7.25 a gallon at the pump in a BP station.

Thing on AvGas both blue 100 Low Lead & green 100 leaded is they have a lower specific gravity than most racing gasolines. Using AvGas and not re-jetted for it, you can burn a piston because the air-fuel ratio is too lean and/or the engine detonated. ...

On compression ratios & octane. There are two ratios static the one you see in the specs & dynamic the one when the engine is running. Cars like the 2017 Honda Accord I4 can run 11:1 CR on 87 because the dynamic CR is lower. The COYOTE does the same thing its static CR is 12:1 (93 recommended) in the 2019 Mustangs but it can run on 87 because the ECU can change the cam timing to reduce the dynamic compression to levels the fuel can tolerate. But you lose power & gas mileage.

Run mine on 93 might do a 100/93 50/50 mix to see what happens. Doing house renovations & the COBRA is trapped in the garage blocked by a 30 yard skip. Getting quality maintenance & upgrade time. Hope to finally get my new instrument package installed. Currently have the base Autometers in the car, going to SpeedHut custom classics

[mikeinatlanta]

Old school engines yes, lots of misinformed guys thought pumping in some higher octane would boost power. Only way to really know what you need is to put it on a dyno. Wayne at VCP tuned my VROD and pushed my timing to the limit with Shell 93. When I'm stuck running 91 I take it very easy on the throttle to avoid detonation. If I move to a state with 91 I'd have to pull a degree out. Reality is that I've never been able to feel a difference with higher octane unless the lower was detonating, but the dyno showed a few hp so that is how I run it.

Recently took delivery of my 18 pickup with the latest 5.0 flex fuel. I'm blown away with how much difference octane makes with this motor. 87 is fine, 93 is much better, and E85 feels like I put a new and aggressive tune in the truck. It's truly a night and day difference. Not sure what all parameters change with the octane, but it's much more than just timing as witnessed by my fuel remaining post earlier. Modern tech is pretty cool. Run cheap when you want and dial up the hp by pumping in the good gas.

[GoDadGo]

Recently took delivery of my 18 pickup with the latest 5.0 flex fuel. I'm blown away with how much difference octane makes with this motor. 87 is fine, 93 is much better, and E85 feels like I put a new and aggressive tune in the truck. It's truly a night and day difference. Not sure what all parameters change with the octane, but it's much more than just timing as witnessed by my fuel remaining post earlier. Modern tech is pretty cool. Run cheap when you want and dial up the hp by pumping in the good gas.

Ditto On The New Truck Mikeee,

I purchased a 2018 VVT 3.6 V/6 Ram 1500 Tradesman over the summer. The truck runs just fine on 87, but 93 seems to be a bit better; however, on E-85 it feels like I have a V/8 under the hood. After that tank of E-85 I changed the oil since it was time (5,000 Miles) but the power increase was significant enough to note.

My plan is to run a tank of E-85 right before each oil change hoping that maybe it will de-carbon my tiny truck engine.

[Dave Howard]

One of the great things about running a Coyote and computer controlled ignition is you don't have to be as picky with the fuel grade. I have my Coyote dyno tuned with 93 octane fuel in the tank. For putting around town and even long tours on the highway I run it on regular 87 octane. The engine runs PERFECT. Do I notice any performance difference - NO. I've had the experience of running with a group of cobra enthusiasts in British Columbia with many different engine combinations. I had the only Coyote and had no issues on 87 driving at sea level through 7,000ft . I can't say enough about how enjoyable the Coyote ride has been.

[turbomacncheese]

I don't know that I would go as far as "most" cars, either, but I DO know that the guy who coached me on my first engine build...well, the first one that didn't need to be rebuilt under 1000 miles - so, my SECOND engine build...had been building and racing motors for nearly 30 years at that point, and told me they used to run the cheap stuff, pull the timing, and pick up some precious fractions of a second on the ET. It was already early 2000s, and he was reminiscing about the good old days, soooooo, I'm willing to be that a lot of it has to do with engine technology and how some of the old-man-wisdom refuses to die.


Well, the first thing that comes to mind is all the native reservations out here. He told me the pipelines carry all sorts of petroleum, not just gasoline. So a pipe might run gas one day, oil the next, kerosene the day after that. They are supposed to run a certain amount of product through when making the changes, and that mixture isn't supposed to be sold with either product. But since the reservations aren't under US jurisdiction, they'd dump it in the tank anyway and sorry for your luck if your truck doesn't run well anymore. I'll ask him for the most outrageous thing he saw, see what he gives me. A lot of the stories were about tax evasion, maybe less interesting here.

Just to clarify, i screwed up. Just gas and diesel in the lines as far as he knows, but that mix where the two meet was the problem. Some companies can apparently separate the two fairly well, but the reservation he was referring to didn't care much if it was done well.