Unleaded 88 vs. unleaded 87

[HDEO]

The likely reason 15% ethanol has a slightly higher octane rating is because ethanol is an octane booster.

What's not to like about it? Well, ethanol has less energy density and is corrosive to rubber and certain plastics. It's basically moonshine. No one would choose to use it if it wasn't government mandated. You will absolutely get better gas mileage using straight gasoline.

It was supposed to help decrease our reliance on foreign oil. But now it's mainly a job creation program for corn farmers and industrial distillers. That's why they wave at you when you're driving through rural Kansas or Nebraska

Keep in mind octane ratings are "minimums." I doubt the blenders are taking chances by adding only the minimum. And you're getting a half gallon of whatever the guy who used the pump before you bought.

I kept a Car & Driver article from a couple years ago where they ran a variety of high performance vehicles and trucks calling for premium on regular. The result was effectively no difference. One saw a slight increase in mpg (less than 1).

Also altitude affects octane that's why regular is 85 in places like Colorado.

The original reason gasolines were oxygenated was to reduce carbon monoxide emissions at cold start in the winter. But yeah it sure grew from there. MTBE was the favorite before alcohols except that it doesn’t break down enough in the environment so when gasoline leaks out of the storage tanks the MTBE migrates and ends up in groundwater. You don’t want to be drinking it. Of course you don’t want to breathe carbon monoxide either.

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[CJBax]

It was Avgas available in octanes 87, 100 and 130. The 130 was crazy fuel in 1970 era cars with cams and dual quads

I had to look up that avgas lol. The widespread use of highly leaded gas like that was definitely before my time. I was surprised to read that so many post WWII piston engine aircraft still cannot run on unleaded fuels. Though I see that globally there are phase-out plans in progress to replace leaded avgas in the near future.

Yeah, at an effective 130 (when running rich) anti knock rating I imagine a capable car engine could generate some serious power numbers, though definitely illegal ever since the prohibition of leaded fuels in road cars.

It would be nice to see some advances in anti-knock agents that could compare to old leaded fuels without the extreme toxicity, though I doubt we'll see anything of the sort while there is no immediate need for it.

 

[Montana Ranger]

We did some tests once and w/ dino saw the more ethanol the more performance dropped. The best results were 100% gas.

Ethanol has a lower heat content by volume than gasoline, so less mileage.
E10 reduces fuel economy by 3% to 4%. E15 reduces fuel economy by 4% to 5%.
E85 by 25%.

 

[FoD]

It was Avgas available in octanes 87, 100 and 130. The 130 was crazy fuel in 1970 era cars with cams and dual quads

I remember Chevron selling a high 100 octane premium at the pumps. Would get it sometimes when there was extra cash, like maybe it was.45 a gallon to regulars .28

 

[JohnnyO]

At the moment E15 88 is only ten cents less than 87 here so I’m back to running regular 87. Which can be up to 10% ethanol anyway.

 

[Trigganometry]

I remember Chevron selling a high 100 octane premium at the pumps. Would get it sometimes when there was extra cash, like maybe it was.45 a gallon to regulars .28

Yup I remember that, don’t want to drive to the airport for crazy fuel. Everyone throw your change into the hat we’re doing 100 tonight! Lmao good times!
We had a burnout road named Milk street. We stole the sign and repainted it to chocolate milk street. Cops weren’t amused at all.

 

[2020XLT]

Thought I would give everyone an update on my use of UNL88. The only gas stations in this area that has UNL88 is Sheetz and the price is currently 25 cents less than UNL87, $2.94 vs $3.19. I have been using UNL88 in my 2020 Ranger XLT and my wife's 2015 Edge since mid July 2020. As of now I have not noticed any changes in performance or gas mileage, just a little bit of savings in my wallet......

 

[Traneman]

Thought I would give everyone an update on my use of UNL88. The only gas stations in this area that has UNL88 is Sheetz and the price is currently 25 cents less than UNL87, $2.94 vs $3.19. I have been using UNL88 in my 2020 Ranger XLT and my wife's 2015 Edge since mid July 2020. As of now I have not noticed any changes in performance or gas mileage, just a little bit of savings in my wallet......

I switched to 87 last couple of tanks, and I saw no changes in MPG on mine, so once this tank is gone back to 88 myself. I get extra savings from our local grocery chain, so I am also way under $3 a gallon.

 

[Racket]

I found this old thread and felt commenting would be amusing since I really got great performance from E30 (double the 3thanol of E15!) and it was barely more xpensive than E10 87 octane. In other threads folks chimed in that turbocharged motors can make better use of ethanol (yay boost) and although Ford doesn't explicitly state E30 is appropriate - let alone E85 - I haven't had problems. If I were to run E85 for the performance I'd want the conversion kit but no one makes it specifically for the Ranger - although ecoboost mustangs have them available. An upgraded intercooler interestingly is recommended.

Having gotten a couple tanks of super expensive ethanol free 90 octane (thanks Kroger points!) I could not detect better performance although my highway MPGs were nearly on par with E10 93 octane.

If the government ends up pushing E15 for whatever perceived reason it won't be all bad as long as it's cheap(er). Our trucks seem to be built to run it and the turbo makes it funner.

 

[Dgc333]

FWIW, there is no reason to expect higher octane fuel to net better fuel mileage, more power but not better mileage.

A 4 cycle engine is most efficient and makes the most power when maximum cylinder pressure occurs at approximately 20 degrees after top dead center (it will vary some based on the design of the engine). In order for that to happen the mixture needs to be ignited before top dead center to give the mixture enough to time burn sufficiently to cause max cylinder pressure at the ideal point. The issue is that lower octane fuel can/will ignite causing detonation before you can get to the ideal timing for max power and efficiency. Higher octane fuels will allow for more timing before detonation and which results in being closer to the idle point for max power and efficiency. All of this applies to WOT which in the overall run time of the engine is a very small percentage.

Now when you are cruising down the road the throttle is barely cracked and the air/fuel going into the cylinder is very limited. This inefficient filling of the cylinder requires even more timing to have max cylinder pressure occurs at the ideal time. Also, because of the inefficient cylinder fill the mixture is much more detonation resistant so that higher octane is not a factor. This is why the advice to drive the vehicle conservatively is good advice. Since you spend 90% or more of your miles driven under these conditions higher octane does not impact your overall mileage. If you pull away from every stop at WOT and go WOT everytime you need to accelerate it may be possible to see some improvement in mileage but you would see a much much larger improvement by driving a little more conservatively.

I would venture a guess that anyone is seeing a measureable mileage improvement with higher octane fuel has subconsciously changed their driving habits.

 

[12Bravo20]

What's not to like about it? Well, ethanol has less energy density and is corrosive to rubber and certain plastics. It's basically moonshine. No one would choose to use it if it wasn't government mandated. You will absolutely get better gas mileage using straight gasoline.

Yes ethanol is nothing but moonshine that has had a denaturing agent added so people can't drink it. There is a big ethanol plant about 10 miles from me and every time I pass while they are brewing the mash brings back memories of making moonshine when I was younger.

I had to repair or replace quite a few carburetors on small engines due to ethanol in the gas until I started using STA-BIL in them. Make sure to get the STA-BIL that removes ethanol. I haven't had any issues since then.

 

[Jason B]

Be careful with ethanol mixes …

As Doc said. Here is what the manual states about Fuel:

 

[mtsoxfan]

FWIW, there is no reason to expect higher octane fuel to net better fuel mileage, more power but not better mileage.

A 4 cycle engine is most efficient and makes the most power when maximum cylinder pressure occurs at approximately 20 degrees after top dead center (it will vary some based on the design of the engine). In order for that to happen the mixture needs to be ignited before top dead center to give the mixture enough to time burn sufficiently to cause max cylinder pressure at the ideal point. The issue is that lower octane fuel can/will ignite causing detonation before you can get to the ideal timing for max power and efficiency. Higher octane fuels will allow for more timing before detonation and which results in being closer to the idle point for max power and efficiency. All of this applies to WOT which in the overall run time of the engine is a very small percentage.

Now when you are cruising down the road the throttle is barely cracked and the air/fuel going into the cylinder is very limited. This inefficient filling of the cylinder requires even more timing to have max cylinder pressure occurs at the ideal time. Also, because of the inefficient cylinder fill the mixture is much more detonation resistant so that higher octane is not a factor. This is why the advice to drive the vehicle conservatively is good advice. Since you spend 90% or more of your miles driven under these conditions higher octane does not impact your overall mileage. If you pull away from every stop at WOT and go WOT everytime you need to accelerate it may be possible to see some improvement in mileage but you would see a much much larger improvement by driving a little more conservatively.

I would venture a guess that anyone is seeing a measureable mileage improvement with higher octane fuel has subconsciously changed their driving habits.

+1...
I drive conservative most of the time. I run 87. I generally get 24in the summer. Switched to 91for a tank. Still got 24 mpg. Not worth the $1 extra per gallon.

 

[Motorpsychology]

Just different areas of the country I guess.
Here in Virginia 88 is 15% ethanol, and ethanol really isn't good for an engine. 10% I gotta live with cause its mandatory, but I'll pass on 15%.
Luckily there are several independent gas stations that still have 87/89/92 octane non-ethanol REAL gas. Use it in my older mowers, lawn tractor.

Never use a n E-15 (15% ethanol blend) gasoline in a powersports engine: motorcycle, PWC, SXS outboard other small gasoline engine: lawn mower, leaf blower, chainsaw,etc. There is currently no such engine designed to run E-15 and never has been.
In fact, it is illegal to use in such equipment nationally:

The Ranger Owner's Manual says it's ok, but not to use E85 (85% alcohol) also called Flex Fuel:

 

[OldBill]

Yup I remember that, don’t want to drive to the airport for crazy fuel. Everyone throw your change into the hat we’re doing 100 tonight! Lmao good times!
We had a burnout road named Milk street. We stole the sign and repainted it to chocolate milk street. Cops weren’t amused at all.

A dirt track racing fan here. A young driver from my town thought he had a great idea by filling up the racecar "a small block Chevy" with 110 octane AV Gas from the local airport. It was way cheaper than the 97 octaine they sold at the speed shop or at the track. He usually ran pretty good but all of a sudden he was way down on power. After consulting with his engine builder he was informed that AV Gas was specially formulated for high altitude and those octane ratings were significantly lower at see level.

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