Octane difference?

My 70 Chevelle 396 needs at least 93 corn fuel to run smooth but seems to run the same on 90 NON Ethanol. Hard where I live to get over 90 real gas but used to be able to get 93 as well. I also notice the same generic gas shipper trucks go to the no name stations as well as name brand ones in Central Florida. Can't make a comment on fuel economy because I have none! LOL

 

at lease gives us the smile per gal...lol

 

Get Gallons Per Mile

 

The only problem I newer boats is when the boat sits for a long time. Older boat motors especially carbureted ones did not come with ethanol resistant fuel lines. The lines would start to deteriorate on the inside. When I had a Black Max I replaced all the fuel lines with ethanol resistant ones and added and inline filters. Black Max's only had a screen at the motor. My Black Max had milled heads and was running 140 lbs of compression so I ran 93 octane. In my area 93 is only available with 10% ethanol. The 2006 Optimax DFI that I have now runs fine with 87 octane 10% ethanol. I run ethanol free mix in my 2 cycle lawn equipment those little clear fuel lines do not handle ethanol well.

 

Just got back to this. Thanks @GODZILLA for the clarification on my post, I guess it was vague.

To be clear, Mr. Mackey says, “Ethanol’s bad. Mmkay?” Or, as Sammy Hagar belts out in The Dream Is Over… “It’s a ripoff!”

It’s just that for some of us, there’s no choice at the pump, depending on where you live. And for others, the price offset for ethanol-free is not worth it and they’d rather go inside and get a 12-pack for their money. And for (I think) the majority, it’s not worth the bother.

All I can say from my E10-15 experience on the small engine equipment is, like yet another bad Food Network show, a drizzle of Seafoam and a teaspoon of Berryman’s B12 go a long way. Otherwise, you end up with varnish and moisture entrained goo in those tiny (read, temperamental) fuel system components just like @GODZILLA has posted.

 

I always use stabilizer and keep the tank topped off if my Break Out Another Thousand sits for periods off time.

 

Shout out to @texasrho83 for the best post in the thread!

 

I have a 95 gallon tank and do not keep it topped off. In 5 years I have only filled it once. That was back in February to beat the increase in gas prices. The Optimax is relatively good on gas.

 

Yeah, older boat fuels did swell up in the inside ad cause fuel starvation or eventually it would gum up and make its way into the filters or carbs. Unfortunately for now I don’t have to deal with boats. I recently got rid of mines. Miami is a shitshow when it comes to boating. It was more a hassle than actual boating. As for my lawn equipment, I haven’t run into any issues using ethanol. I know the clear lines don’t like it but easy to change. I also don’t have many, very few actually, non ethanol stations. Plus down here it ranges from $1to $1.20 more per gallon.

 

Nope. Octane and ethanol are 2 different things, separate from each other. Octane is a number that tells you how stable the gas is against pre-combustion, pinging, detonation, whatever you want to call it. Ethanol is used now instead of MTBE. MTBE is/was used to oxygenate gas for a better burn. Now they use ethanol.

Better to what extent? For normal everyday driving you won’t notice any difference between all 3 grades, 87, 89, 93. I know there’s mores grades or different ones, but these are the grade here in FL. Now for anything other than just normal driving, ah maybe. But I made an example of prices and mpg that in the end pretty much a waste to use anything above 87. I ain’t going to lie either and say I was on the same boat before but ultimately getting all worked up over octane, oils, trans fluids (low&high octane ones),lol, is kinda pointless since most people never keep their vehicle long enough to reap the benefits, if any. I stick maintenance and just enjoy the truck.

 

I heard you on the Miami shitshow. I see the Miami boat ramp reels. There are quite a few people out there that have no business owning and driving a boat. I have seen reels that make Rodney Daingerfield look like a real skipper.

 

I understand what you're saying. However it doesn't jive with what people have proven.

I'm trying it myself now, measuring the MPG for two or three tanks of "mid grade" vs the same number of tanks for the "cheap stuff". And I'm doing the math myself instead of relying on the dashboard.

 

Total respect for this - please share your results when you have all the data. Also, for manual record keeping, using voice over to Bluetooth to your phone is a great way to time stamp and get all the details in one place.

 

What have people proven? If you look back I posted some numbers. I did simple math. Price of gas vs mpg vs total cost. It take the tundra getting 3 additional mpg to make it worth it. Even if you get 2mpg better it’s still more expensive buying 93. And since the tundra can’t magically make 3 more mpg just by switching to 89/93, it a waste. If your doing your test, more power to you. I have also done them so don’t think I knocking you. I would like to hear your results. Mine where always the same. No savings from 87-93. 89, can’t really remember. If it broke even total cost wise, then no point in using it. It’s all the same gas.

Also why the “cheap”? If by cheap you mean a rundown gas station, then yes, they would have crap gas. But if you mean 87 from top tier gas station, then that a wrong assumption. All grades of gas have the same BTU and additives from their manuf. Fun fact: all gas starts out the same. It all comes from the refinery. It is then sold to Shell, Mobil, Chevron, etc where the company puts their proprietary additives package. Some put the bear government minimum and others go above(top tier gas).

This whole posted started because the OP has 90+k on his tundra and was wondering why the gain (supposedly according to him) of mpg. Higher grade gas, if it helps just masks the issue. Parts and sensors don’t last forever. Matter of fact his O2 sensors are pretty much shot which is a key component into regulating air/fuel ratio which inter translates to mpg.

 

Yup

I pass the place where the fuel trucks fill up

all brands same station

 

Hey @nobodyintexas - I work in midstream and you’re right - the “base” gasoline (controlled by product specifications) for each grade are the same, but the formulations (what I simply call “solvents” ;-)) they mix in are different like @pursuit2550 mentions above.
So yeah, guys, at those truck terminals, you’ll see all various brands filling up right next to each other. The terms “Top Tier” and the numbering you see in this post are not terminology that mean anything in the industry.
And #sorryImNotSorry, but ethanol is nothing more than a political football and ultimately a ripoff to the American consumer.

 

Ethanol is a scam. So much that the US still produces MTBE and sells it other countries. Interesting how we switched to ethanol because of global warming or whatever they are calling it today but yet we export it. If it was so bad we wouldn’t even be making it.

 

Sorry for not being clear. 'cheap' meaning lowest grade, which I think it 87 here. I'm comparing with 89. I haven't seen any evidence that premium is worth it.

 

It might not be the octane but the ethanol content. Where I live 87 has up to 15% ethanol, 89 up to 10% and 91 has zero ethanol...of course this doesn't apply to every brand. 91 is the only octane you can get no ethanol (again, where I live) and it is becoming very hard to find. Ethanol has a lower energy content than gasoline, so naturally you'll get improved gas mileage the less there is in your blend. As for performance I am not sure if octane it makes a difference in the Tundra. I run 91 just for the no ethanol content because I have the 38 gal. tank and I don't drive a lot so the gas tends to sit, pure gas lasts about 6 months vs ethanol blends which last significantly less.

Long story short, your usual 87 octane gas has ethanol in it and you bought some 90 with no ethanol

 

This and so many other unaccounted for variables. The energy content in a gallon of fuel can vary several % just based on temperature alone.

 

Interesting. I have never heard of any gas with 15%. Down here we have 87, 89, 93 all 10%. Then we have non ethanol 90. But that shit is always about $1 to $1.20 more per gallon.

 

Different in Texas. Ethanol free when you can find it is 87. Ethanol is used to boost octane. Other then Ethanol free in 87 all others are 10%.

 

Once again, it’s good to have a great laugh early in the morning. I am speechless right now. With today’s technology, like a computer, tablet or smart phone, that people really believe what they say.

https://www.eia.gov/energyexplained/gasoline/octane-in-depth.php

https://www.eia.gov/energyexplained/gasoline/

https://www.aaa.com/autorepair/articles/don't-confuse-gasoline-octane-and-quality

https://www.eia.gov/energyexplained/units-and-calculators/british-thermal-units.php

I will leave this here. Just a few sites. Maybe know what you’re talking about before you post. I won’t even bother with the rest of your post.

 

I have a 2006 Honda Ridgeline. The manual said to put in premium if towing. I was bringing the Chevy to NJMS and put premium in on the way down. I made it down in one tank. One the way up I had to refill and I put regular. I had to stop for a refill. My assumption is the truck has a knock sensor. When it senses knock in the engine it retards the timing. That knock the bottom end out of your performance and gas mileage.

I tried the same "experiment" with the Tundra. I saw no difference in MPG or performance.

On of our past memember is a Shell engineer. This is what he said:

"Hi, there is potentially more but more likely different detergents. It’s all about cost. My recommendation would be to buy and additive and not use the premium. You’re wasting your money as your engine is designed for regular. Premium is harder to combust, higher octane, harder to combust. When it does combust, bigger explosion=more power. That’s why avgas and stuff is 102-104 Octane, or somewhere around there. If you don’t want to buy and additive then the premium is ok but I wouldn’t do that too much. It’s extra strain on your engine and you may end up with more gunk on your cylinders since you can’t combust all of it. Feel free to post."

Also, on my 2020 Tundra I did the same experiment. No change to the MPG.

 

Petroleum engineers | Toyota Tundra Forum (tundras.com)

WHAT GRADE FUEL ARE YOU BURNING???? | Toyota Tundra Forum (tundras.com)

 

Did you bother to read what I posted or did you just decide to talk more ignorant crap. Octane has nothing to do with BTU.

 

Did you account for wind direction and speed both ways? I drive north south quite a bit during deer season and have seen a swing of close to 4 MPGs. Up almost 2 with a tail wind and down almost 2 with with a head wind. These were extremes. Like 30 mph with higher gusts. We get some nasty fronts rolling through in November and December.

 

If you stick behind a semi driving 50, I’ll bet you only use ½ tank

 

I guess all the sites that say that gas has the same BTU are wrong. I also guess the U.S. EIA is wrong since and I quote "Octane ratings are measures of fuel stability". Propane and Natural gas is like comparing apples to oranges. Oh my god, you can't be serious right now. That's like comparing gasoline to diesel BTU's. And this is your job. But you know what, I am going to go and buy Octane Booster at the parts store right now so I can have more power.

 

Personally - I use only non ethanol fuel.

It’s just easier and precautionary - I use my truck very little - so a 38 gallon tank might last me months - I don’t like ethanol fuel sitting more than 30 days collecting moisture from humidity.

No negatives - but for the price of 92/93 around here - you get 90 pure gas - I think it performs as well if not better and since I can just keep a supply on hand for various equipment - can fill my truck up in a pinch too.