People think using higher octane gas is better?

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Well, now you just edged over into a different topic......Winter fuel vs. summer fuel. If you were dealing with summer fuel of those rating, used in winter, there might be a very slight advantage, but only on startup.

Winter fuels have their vapor pressure ratings adjusted, so the difference between starting for differently octane rated winter fuels would be insignificant, as far as initial startup is concerned.
 
Quest, my Mazda3 is a 2012. It lacks the 4-2-1 exhaust manifold of the 2014+ engines so it runs 12:1. The 2014+ runs 13:1. Japan/Europe spec is 14:1. Mazda gleaned that Americans are loathe to run expensive gas in an economy car so the compression ratio was lowered for the States.
 
Originally Posted By: DBMaster
Quest, my Mazda3 is a 2012. It lacks the 4-2-1 exhaust manifold of the 2014+ engines so it runs 12:1. The 2014+ runs 13:1. Japan/Europe spec is 14:1. Mazda gleaned that Americans are loathe to run expensive gas in an economy car so the compression ratio was lowered for the States.


Thx for the info. So, it sounds like your engine is capable of slightly higher output (ignition mapping) than that spec'ed for 87. In other words: running 91 or higher may give you slightly higher output (ignition timing can advance a bit further until the 1st knocking sound detected).

Run 87 octane gas for everyday (non-critical) use; run 91 or better for spirited driving.

Have fun!

Q.
 
Originally Posted By: double vanos
Although Ford says you can run 87 octane fuel in the 3.5 Ecoboost engine, owners including myself might want to consider running a higher octane fuel because of low speed pre ignition (LSPI). Soot in the oil is an issue as well.

Interesting read here: www.gf-6.com
Check out the article about turbo gas direct injected engines.


Premium 91 E0 makes a world of difference in my ecoboost. It runs much smoother and gets better mpg. (15.7mpg on 87E10 to 18mpg on 91E0 on average)
 
I may consider trying mid-grade and premium, for grins, once it gets warm again. In the "winter" (quotes because this is Texas) I already feel a performance boost due to not running the A/C compressor. Even in my 6.6 liter Pontiac I noticed performance losses when running the A/C.
 
Originally Posted By: Doog
Originally Posted By: stygz
Do people really think it is cleaner or better just because it is more expensive?


Not me. I have owned 3 Lexus vehicles that all call for 91 octane. In an accumulated 430,000 miles (so far) none have had anything but tier one 87 octane. Each have gotten a Techron or Regane fuels system additive every 20,000 miles and new air filter every 20,000 (Fram). All were tuned up with new spark plugs once at 120-140,000 miles and the throttle body cleaned.

The results: Zero pinging. 28-32mpg. clean TB.

The experiment continues.

FWIW the engines 2- 3.5L and one 3.3L V6 all run on 5w30 syn oil OCI 5000


What happens with your car may vary to someone elses. Lexus and Toyota both recommend "Top Tier" Fuel. So I feel this would be more important than the octane rating UNLESS premium fuel is required.

Mind you too, that most Lexus and Toyota are equipped with VVT or VVT-i technology, so using a lower octane may not "hurt" your car, I bet if you dyno'd your car with a tank of 87 vs 91 or 93 octane fuel, you are losing at least 10% hp. Now that may not be measurable by the "Butt Dyno" but your car sure notices the difference.

Your opinion is subjective. Though, your right, your car is proof it can run on 87, but why sweat an extra $1.50 to $2 a tank of gas if you can afford a Lexus to begin with?
21.gif



Jeff
 
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Originally Posted By: stygz
Awhile back I bought a new Pathfinder and a buddy had a newer truck. He told me I should use a higher octane gas instead of the recommended 87. Do people really think it is cleaner or better just because it is more expensive? A person would just be better off going to a newer name brand gas station that maintains their facility very well.



Higher octane doesn't do anything for my Escape. It does a lot for my skayctiv mazda3.
 
Originally Posted By: volk06
Originally Posted By: double vanos
Although Ford says you can run 87 octane fuel in the 3.5 Ecoboost engine, owners including myself might want to consider running a higher octane fuel because of low speed pre ignition (LSPI). Soot in the oil is an issue as well.

Interesting read here: www.gf-6.com
Check out the article about turbo gas direct injected engines.


Premium 91 E0 makes a world of difference in my ecoboost. It runs much smoother and gets better mpg. (15.7mpg on 87E10 to 18mpg on 91E0 on average)


All engines that i have come across (2 or 4 wheelers) that frequently go NEAR or just PLAIN GO ON the redline of the rev meter (doesnt matter if its 5500 (toyoya corollas) or 18000 RPM (honda hornet 250) to redline) benefits alot from both a higher octane + PEA based cleaners.

one heck of a difference imho.

It also depends on the driver; i like to go sport mode after warming up , makes alot of a difference ; my buddy who owns the car runs it at 2000-2500 rpm for fuel economy reasons (cant tell, he just tops up the cheapest gas he finds).
 
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Originally Posted By: 4wheeldog
Well, now you just edged over into a different topic......Winter fuel vs. summer fuel. If you were dealing with summer fuel of those rating, used in winter, there might be a very slight advantage, but only on startup.

Winter fuels have their vapor pressure ratings adjusted, so the difference between starting for differently octane rated winter fuels would be insignificant, as far as initial startup is concerned.
Winter fuel has more butane, which just happens to be cheaper.
 
There was a time when "High octane" was made by throwing in a lot of a lead compound which played havoc with the mingy ignition systems ability to fire plugs before electronic spark generation. 6000 miles was not an unusual lifespan for plugs. I switched to a "CDI" system on a 71, it fired the plugs fine, but put the stock plug wires to the test.
 
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Does anyone have any info on which fuel additive type PEA vs what is it PEO or something like that? I get them mixed up haha. I just have not be able to find much. I thought that one was better in that it left behind less carbon deposits than the other?

Just curious if anyone came across anything like that here.


Jeff
 
Originally Posted By: Jeffs2006EvoIX
Your opinion is subjective. Though, your right, your car is proof it can run on 87, but why sweat an extra $1.50 to $2 a tank of gas if you can afford a Lexus to begin with?
21.gif

Jeff


At least in our case, over time, saving $2 on each tank of fuel adds up ... on our Lexus with 195,000 miles, that equates to a little over $1200. A penny saved is a penny earned. As always, YMMV.
 
Like many here, I've wondered. The compression on my Regal's NA 2.4 engine is fairly high, 11.2:1 or something like that, so some her suggested I might try 91 and see.

Results have generally been: Yes, some improvement in mpg (but not enough to pay for the soaring price difference between 87 and 91 around here), and a subjective sense of "peppiness" that could well have been my imagination.

On my next highway road trip I'll use a tank or two of 91 and see if there's a noticeable improvement while the car runs at a steady speed. But otherwise, I'm sticking with regular for now.
 
Originally Posted By: Curtis Newton
Originally Posted By: Jeffs2006EvoIX
Your opinion is subjective. Though, your right, your car is proof it can run on 87, but why sweat an extra $1.50 to $2 a tank of gas if you can afford a Lexus to begin with?
21.gif

Jeff


At least in our case, over time, saving $2 on each tank of fuel adds up ... on our Lexus with 195,000 miles, that equates to a little over $1200. A penny saved is a penny earned. As always, YMMV.


You could save a lot of pennies not buying a lexus.
 
Originally Posted By: badtlc
You could save a lot of pennies not buying a lexus.


True; however, from my experience, if you hold onto vehicles for a long time, you just can't beat the quality of the product for the pennies spent.
 
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If the ecu advances/retards the spark to suit the octane, then you should use the highest available grade that your car can adapt to

If your timing is fixed, the lowest grade that doesn't ping would be cheapest and the highest grade available might not hit max cylinder pressure until too late in the stroke - dyno time will tell you quicker than seat time which suits the motor best but seat time lets you feel the differences and pick the compromise that suits you best
 
Regular gas in the UK is 95 octane? (from the video)

I wonder how that is calculated and what its U.S. equivalent is.
 
From Wiki:

Quote:
Anti-Knock Index (AKI) or (R+M)/2
In most countries, including Australia, New Zealand and all of those in Europe, the "headline" octane rating shown on the pump is the RON (research octane number,) but in Canada, the United States, Brazil, and some other countries, the headline number is the average of the RON and the MON (motor octane number,) called the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2). It may also sometimes be called the Posted Octane Number (PON).
 
Thanks, Kiwi. I should have looked that up myself, but hey, if someone else will do it for you... 8-D

That makes it difficult to compare the regular fuels. Do you happen to know what the AKI is of the regular fuel in your neck of the woods? I am almost willing to bet that it is higher than 87.
 
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