Octane (ex: 94 vs 92, etc.)

[TripleTransAm]

A few weeks ago, I contacted an old friend who works in the gasoline industry (he works for one of the larger petroleum companies) and picked his brain about octane and stuff. I figured I'd share some of the comments made about octane and different gas companies.

Every company uses a different additive package. Some work well, others not so well, some work better in some cars than others. When it comes to comparing octane, though, I was told it's not an "apples-to-apples" comparison.

Some companies use ethanol as an octane enhancer. While this does result in a fuel with greater resistance to detonation (ie. pinging), ethanol supposedly has less energy per unit quantity. In other words, burn an ounce of gasoline and an ounce of ethanol and supposedly the ethanol releases less energy in total. So while the ethanol-enriched fuel has a higher octane rating, it is 'diluted' with a substance that releases less energy during combustion.

This leaves us with a dilemma: allow the PCM to dial in its most aggressive timing without spark knock, or choose a fuel with greater energy per unit quantity burned.

I just went through my first and only tankful of 94 octane. During the fillup a few days ago, I noticed a small sign saying the fuel could contain up to 10% ethanol. Sure enough, with not much change in driving style (perhaps even more economical), my mileage dropped from a 19.xx average to about 17.25 for this tankful.

I'm not saying that higher octane and low fuel mileage go hand in hand, but fuel quality may have a greater role in performance than just pure octane ratings. Interestingly enough, my 1998 WS6 has pulled its best 1/4 mile numbers and overall fuel mileage with 92 octane of one brand of gas than with two particular other brands of 94 octane gas!

[MMM2003]

Hey Triple T,

got another question for you. Maybe you can pass that along to your buddy in the Petrol industry.
Since you are in Canada, I'm wondering what method is used to determine the Octane rating.

I know that here the US the (R+M/2) is a standard. In Europe the RON rating is used (usually 8-10 points higher).

What do they use in Canada?
I'm just curiuos.

[TripleTransAm]

Originally posted by MMM2003
Since you are in Canada, I'm wondering what method is used to determine the Octane rating.


I'm pretty sure it's the same as in the US.

It's usually noted on the pumps themselves... I'll have a closer look next time I fill up (which won't be too long from now with the distance I travel per week).

FWIW, I noted best mpg with Exxon 92 back when I pulled my successive 33mpg runs with my WS6. This is consistent with the performance I get with the local Esso 92 (same company, I believe). What gets me upset lately is that Esso's 92 seems to have decreased to 91 for some reason. Darn it, it was my favorite gas (and what prompted me to try a competing brand's 94 in the MM earlier).

[RF Overlord]

I don't have the owner's manual in front of me, and it's raining, so I'm not gonna go retrieve it...

I believe the book says 91 octane...Dennis's chip re-calibrates the fuel and timing tables, requiring the mods (plugs and 'stat) that he specifies to run properly on 92. From what I've read in numerous publications, running a higher octane than the car can use is a waste of money. It would seem that running 93 or 94 octane would not be of benefit, except to Exxon...?

[Kelly]

non-oxygenated 92 used in my neck of the woods, for collector cars and motor bikes and such is all that we have here other then the 87 octane, MM runs like a top on it.

[TripleTransAm]

Originally posted by RF Overlord
I believe the book says 91 octane...

I believe you're right. Personally, I'm more interested in the additives package as long as I maintain the minimum recommended octane. However, I'm just PO'ed that my favorite brand of gas seems to only be available in 91 octane instead of the previous 92. :mad: I really did like that gas.

[looking97233]

Correct, as long as the octane of the gas meets the requirements of the program, 91 for stock or whatever your chip is programed for, the car will run as aggressively as it is programed for. Only when it senses knock from poor gas will it retard the program. Having said that, the car does not care if you are running 100 octane, if it is not programed for it, it will not help.

[drkknight196]

Interesting thread -- I haven't seen a pump in a long while indicating the gas was cut with ethanol .......... is that primarily a northern thing?

[RCSignals]

On a recent trip to BC I noticed a lot of 96 rated premium. Never noticed that here in Oregon.

[notacop]

whahh? i can only get 91 octane here in az. is this normal? i would like to run 92 if i get dennis's chip but would really hate to mess with cans of octane boost. i've been all over az and the best i've found is 91 (i believe we might have had 92 or 93 when i was just a kid, ha). does anyone know why this is? it might just be another reason why arizona sucks in my opinoin. j/k ha:D

[looking97233]

RC- Don't tell me you are just figuring out how badly our gas sucks? Here in Oregon, we have an amazing state gas tax of 24.5 cents per gal(Highest in the country). However there is no state quality controls in place. I usually go up to Vancouver, WA. to fill up. Just seat of the pants impression, but I believe the car runs better. It does however, get better millage from the gas from Wa.

[RCSignals]

Looking, I figured that out. I was under the impression that standards of some kind were imposed a couple of years ago though.
Vancouver WA is a little far for me to go to buy gas LOL

I pretty much use Chevron exclusively now. they are the only ones that seem to have any consistency here, and I understand their gas does come from their refinery

[looking97233]

Standards? Here? It's a new one on me. My understanding is that the gas itself all comes out of the same tanks. Over by the St. Johns bridge on hwy 30. I too use cheveron, I think that thier additive package may be better than others.

[TripleTransAm]

Originally posted by notacop
i would like to run 92 if i get dennis's chip but would really hate to mess with cans of octane boost.


Here's something I've heard from several sources, but obviously cannot comment on it since I lack the necessary chemistry lab.

Those cans of octane boost that boast "up to 2 full points of octane" or "boosts octane by 2 points" or whatever they claim... this supposedly misleads folks into thinking that if they add this to 92 octane, they get 94. The story I heard is that it adds 2 decimal points... ie, you get 92.2 octane when added to 92 (using the example of 2-point booster).

Something to think about. I'd obviously appreciate corrected info if this is not the case.

[TripleTransAm]

Originally posted by drkknight196
Interesting thread -- I haven't seen a pump in a long while indicating the gas was cut with ethanol .......... is that primarily a northern thing?


Dunno. Could be a new local legislation thing, requiring pumps to indicate if the gas contains any dilution of any kind. Or, maybe I just never noticed it before.

[RF Overlord]

Originally posted by notacop
whahh? i can only get 91 octane here in az. i would like to run 92 if i get dennis's chip but would really hate to mess with cans of octane boost.

Dennis can adjust his programming for whatever octane you require, within reason. A chip optimised for 91 may be a little less aggressive, but you will still get all the other benefits his programming provides, especially the transmission improvements. Call him...he can help you... :D

[darebren]

i always get the highest octane at whereever i am. is that wrong, is there a certain rating we should use? see sig for mod list...once i even dropped in some 104 octane boost just to be on the safe side...maybe i need to pay attention to something...

[RF Overlord]

dare:

Unless you discussed it with Dennis and he programmed your chip for something else, it's most likely programmed for 92 octane, so using anything more than that will do nothing for you.

You may also want to be careful using aftermarket octane-boosting additives...they can foul the plugs, and I've heard they can play funny tricks with the o2 sensors...

[SergntMac]

Great thread, lots of thoughts bouncing back and forth. Can't pick any particular post to point to, but many of y'all have been talking about Dennis' chip and what it's programmed for, when it could be the other way around.

Any performance chip from anyone should be viewed as a general "one size fits all" performance mod. The tricks the chip can produce are endless, but the chip has to produce uniform results across a wide spectrum of variables. So, as I have recently learned myself, I'd say any performance chip out there, is just getting you warmed up.

If you wanna really kick butt, and get the best performance and mileage possible with the gas YOU buy everyday, get yourself hooked up with the power tune guys from www.FordChip.com They are friends with Dennis, know his programs, and how to tune the MM. I got mine a few weeks ago, and I can't explain how much better this Girl runs.

The change in my car was phenominal, look 'em up, you won't go wrong. Even bone stock MM can benefit, well worth the effort to get it done.

[notacop]

Originally posted by TripleTransAm

Those cans of octane boost that boast "up to 2 full points of octane" or "boosts octane by 2 points" or whatever they claim... this supposedly misleads folks into thinking that if they add this to 92 octane, they get 94. The story I heard is that it adds 2 decimal points... ie, you get 92.2 octane when added to 92 (using the example of 2-point booster).



wow, that would render octane boost completely useless! has anyone else heard of this---errr scam?

[TripleTransAm]

Originally posted by notacop
wow, that would render octane boost completely useless! has anyone else heard of this---errr scam?


I honestly don't think it's a 'scam'. If this is all true, I think it's more a case of misinterpretation by the consumers. I don't think there's any wording that outright claims the exact number of octane change... you won't see them say stuff like "add this to your 92 octane to get 94 octane!!!" etc...

I just did an internet search on the subject and this web site seems to be in agreement with what I've previously heard.
http://www.biznetonline.com/12-01/car.htm

This site also has some talk of the 'energy content per quantity of fuel' stuff I posted initially.
http://www.angelfire.com/ar/dw42/tech/octane.htm

[notacop]

well they got me. good stuff to know.

[jgc61sr2002]

The only additive you should add to your tank is preimium fuel. I beleive that they are all BS. IMHO. John

[TAF]

I'm not a "conspiracy theorist"..so I can not go with the notion that the "great oil giants" have pulled the wool over our eyes all these years.

However, I do believe that the refining and additives DO make a difference. Premium gas does NOT equal Premium gas.

I go with 93 Octane Amoco/BP...ONLY!!!

[RCSignals]

Doesn't it say in the manual that adding off the shelf fuel additives may be detrimental, and could void the warranty?

[TripleTransAm]

Originally posted by RCSignals
Doesn't it say in the manual that adding off the shelf fuel additives may be detrimental, and could void the warranty?


Probably, but that's most likely just a blanket warning to free themselves of any liability if someone decides to put some real junk in the MM's fuel tank like, for example, lead additives because "them engines need them valves lubricated 'specially if you've got 4 of 'em. Back in the mid 70s, I ran just straight unleaded premium in my 1965 427 and burned up the valves good!"... you get the point.

You'll notice they also strongly recommend the use of Ford motor oil and filters in the car as well. Again, just something to cover their asses.

That being said, I won't put anything in the tank other than good gas (and the occasional fuel injector cleaner depending on whether I feel it's needed).

[RCSignals]

I don't think they are talking lead additives. You have to hunt for real lead additive anyway (although it is available)

[cruzer]

To ask another question, is anyone using fuel from the big retail firms (Wal-Mart, Kroger, Tom Thumb, etc) and what have you found? There is over$.20 a gal difference down here in TX. I asked one manager what his fuel source was and he said they only purchased from "major" suppliers ?????????/

[schuvwj]

I tried 6 gals of 100 octane (about $20.00) and the rest 93 octane when near empty this week and I like the improvement of torque based on my butt in the seat!

[Macon Marauder]

Originally posted by cruzer
To ask another question, is anyone using fuel from the big retail firms (Wal-Mart, Kroger, Tom Thumb, etc) and what have you found? There is over$.20 a gal difference down here in TX. I asked one manager what his fuel source was and he said they only purchased from "major" suppliers ?????????/

I use the Kroger regular gas (87) in all my other vehicles. I've been filling up my wife's mini van nearly every Satruday for more than a year. No problems. My Mustang seems to like it too.

No experience with the premium, though. But I can't imagine why it would be any different...

[RF Overlord]

cruzer:

In New England, Stop & Shop (a supermarket chain) has stations at some of its bigger stores...my wife fills up at one every time she goes off-Cape on business; on special days (Wacky Wednesday and Silly Sunday or some malarkey) their prices are 15-20¢ cheaper than any place local...the Blackbird seems to like it just fine...