question about octane ratings

[shanetrain]

What's up guys, thought I would put this question across to people that may have some knowledge on this.

I have 3 vehicles and all of them say the minimum recommended octane rating for the cars are 87. Well, in good ol' Utah here, regular gas is 85 and mid grade is 88. Being that gas prices are ridiculous, do you think it's going to kill my vehicles by going to the regular unleaded?

TIA

[Stephano]

Utah octane ratings suck. It would help to know what you drove.
If you drive a GT-S Celica ya better run higher than 85.
I personaly put the highest octane I can find usually Sunoco Ultra 94.

[shanetrain]

I have a '99 Rangerv XLT extended cab, my '01 Celica GT and the newest addition, an '03 Durango SLT, (I have 4 kids and the wife, gotta get 'em around somehow). All 3 of them the minimum octane rating is 87.+

*edit: spelling.

[h1coupe]

vouw those are low octane ratings!! the lowest we get over here on Iceland is 95:)

[n2oxide]

shane, i would not go below the recommended rating. without some timing retardation, you could get some detonation... which will destroy your engine in the long run.

*Quick tutorial on octane if you need it - the rating (85,87,89) corresponds to the fuels tendency to combust at certain heat/compression levels. when you have a high compression engine (usually the sporty cars like the GT-S), it requires higher octane fuel so that the fuel doesn't combust prematurely. it's fine to go higher in octane, but lower than your recommended is not good.

but yeah, i feel ya.. gas is gettin kinda out of hand here in socal and being a high school student that can only work a part time job doesn't help.

[oldster]

Originally posted by shanetrain
What's up guys, thought I would put this question across to people that may have some knowledge on this.

I have 3 vehicles and all of them say the minimum recommended octane rating for the cars are 87. Well, in good ol' Utah here, regular gas is 85 and mid grade is 88. Being that gas prices are ridiculous, do you think it's going to kill my vehicles by going to the regular unleaded?

TIA

What is your altitude? I have several vehicles that require 87 by the manual but I run 85 with not problems here. That was confirmed by my Toyota dealer also.

[oldster]

Originally posted by h1coupe
vouw those are low octane ratings!! the lowest we get over here on Iceland is 95:)

Different rating systems I would imagine.

[shanetrain]

Oldster, i'm @ 4500 feet.

[oldster]

Originally posted by shanetrain
Oldster, i'm @ 4500 feet.

You should have no problem using 85.

[F22-Raptor]

I don't know if I would take the chance tho. I mean it is only max 1.50 difference in price for the whole tank. I would use 87 just to be safe.

[oldster]

If it's good enough for the manufacturer it's good enough for me unless you have some other data to prove otherwise.

[F22-Raptor]

The toyota dealer is not necessarily a good representation of the manufacturer. Toyota could easily say you didn't put 87 in it and not cover your warranty. whether the dealer does or not is a tossup. But I am not going to cheap out 1.50 when I just paid 20k for the car :)

[oldster]

Yes I'm sure that is their plan, deny warranty. :rolleyes: Ok, next question, if you had a car with a distributor ignition system that called for an intial timing setting of 5 degrees BTDC in the manual, where would you set it for optimal performance at an elevation of 4500'?

[F22-Raptor]

I didn't say they would just saying they could. BTW you would want to retard timing about 2 degrees max or 3 degrees BTDC due to the fact you are getting more air in the chamber causing your engine to run lean.

[CreepingJeff]

Originally posted by oldster


What is your altitude? I have several vehicles that require 87 by the manual but I run 85 with not problems here. That was confirmed by my Toyota dealer also.

me too. dealer said it was ok to run 85. i would rather run 87, but it's too expensive... so i'll stick with regular unleaded.

[oldster]

Originally posted by F22-Raptor
I didn't say they would just saying they could. BTW you would want to retard timing about 2 degrees max or 3 degrees BTDC due to the fact you are getting more air in the chamber causing your engine to run lean.

Wrong on all counts, you would advance the timing approx. 1 degree per 2,000' and you are getting less air at altitude so would be running rich.

FYI, if you moved the timing from 5 to 3 degrees BTDC you are advancing the timing.

[F22-Raptor]

Originally posted by oldster


Wrong on all counts, you would advance the timing approx. 1 degree per 2,000' and you are getting less air at altitude so would be running rich.

FYI, if you moved the timing from 5 to 3 degrees BTDC you are advancing the timing.

Thats interesting I checked my answer with two "lifer" auto mechanics and their words were verbatim to mine. so we must all be dumb. But you know you are always the first to side with toyota for doing something right with their marketing so why would they be wrong in their manual about what gas to use? But good luck to ya with using 85. I personally don't think 1.50 is worth all the fuss.

[oldster]

I didn't call anyone dumb, but, if they believe you retard timing at altitude and you would be running lean because of a higher atmospheric pressure then I wouldn't be taking my car to them. I was simply answering the man's question. How much 85 octane do you think they would sell up here if it couldn't be used in any cars?

What does my opinion of Toyota marketing have to do with this coversation? If his manual is incorrect than so is mine on 3 completely different year and models, some coincidence heh? By the by, I particularly liked your earlier remark "The toyota dealer is not necessarily a good representation of the manufacturer". Who would you suggest, Pepboys, AutoZone?

[CreepingJeff]

:popcorn:

[GMSeasonedTech]

QUOTE-"You should have no problem using 85" -posted by oldster

-yeah, you shouldnt, as long as your driving a motorcycle. come to think of it, I wouldnt use 85 octane in my lawn mower. No offense to your "knowledge" of course oldster, but low octane causes what we wrenches refer to as "low octane ping" which in my professional opinion, damages an engine.

QUOTE-"If it's good enough for the manufacturer it's good enough for me unless you have some other data to prove otherwise."-posted by oldster

Years ago, some car manufacturers believed in, and reccomended
Valvoline oil for use in their cars. How many here use Valvoline oil? What my point is, is that Toyota is not a good source for information such as this. People who believe that the Car Dealer can do no wrong have a painful truth coming one day. Believe me, I worked for GM. For a dealer to tell you that you can use low octane fuel in their cars is for one thing, a selling point. Thats right, even after you have bought it. Once word gets around that you can burn cheap fuel in there cars and get away with it, then that brings new, more naive customers.

As far as timing per altitude, most new cars have comp controlled timing, that adjusts with sensors. But in the case of a distributor ignition...Well, lets just say i wouldnt ask someone on a message board, there are plenty of credible websites and other sources of info that can be tapped for such an important issue.

Summary- oldster, dont spread your wings if you cant fly.

~GM~

[oldster]

You presented absolutely nothing valid to the conversation as to whether 85 octane would be safe to use instead of 87 at an altitude of 4500'. If you are one of the "lifer mechanics" that gave Raptor the information that you retard and get lean at altitude then I would suggest you take some refresher courses on basic physics.

Summary - GMseasonedTech - you get what you pay for so I'll take a tire rotation please.

PS - I raced for many years at altitude so am not relying solely on Toyota for information.

[GMSeasonedTech]

QUOTE-"PS - I raced for many years at altitude so am not relying solely on Toyota for information."-posted by oldster

Raced which, go-carts or hot wheels? Playstation2 doesnt count.

QUOTE-" You presented absolutely nothing valid to the conversation as to whether 85 octane would be safe to use instead of 87 at an altitude of 4500'."

Let me refer you back to my original post where i said , and I quote."come to think of it, I wouldnt use 85 octane in my lawn mower. No offense to your "knowledge" of course oldster, but low octane causes what we wrenches refer to as "low octane ping" which in my professional opinion, damages an engine."

I believe that was a valid point. As far as you saying that if its good enough for the man, its good enough for you, well that just goes to show how very inexperienced you must be. Cause god knows that a watchful entity like the dealer has never been wrong about anything. If Toyota isnt your only source then why did you post What Toyota confirmed? All you did was dance around the information that i provided with your brainchild rhetoric.

Your handle says oldster, but your posts scream youngster.

-GM-

[oldster]

NHRA brackets, 440 Cuda.

You keep dismissing the altitude equation of which you obviously know nothing based on your earlier conclusions regarding timing and air fuel mixtures. If the car in question was in CA or God help me Ohio then we wouldn't be having this discussion, he should run 87. Why would I not use Toyota as a confirmation, that is what the man drives. What information did you provide that is relevant to the coversation, hmmm, let's see:

1. yeah, you shouldnt, as long as your driving a motorcycle. come to think of it, I wouldnt use 85 octane in my lawn mower. No offense to your "knowledge" of course oldster, but low octane causes what we wrenches refer to as "low octane ping" which in my professional opinion, damages an engine."

How helpful, tells us lots about the effects of atltitude on fuel distribution, effective compression ratios and timing.

2. "Years ago, some car manufacturers believed in, and reccomended
Valvoline oil for use in their cars. How many here use Valvoline oil? What my point is, is that Toyota is not a good source for information such as this. People who believe that the Car Dealer can do no wrong have a painful truth coming one day. Believe me, I worked for GM. For a dealer to tell you that you can use low octane fuel in their cars is for one thing, a selling point. Thats right, even after you have bought it. Once word gets around that you can burn cheap fuel in there cars and get away with it, then that brings new, more naive customers.

Am I supposed to read between the lines here, what the hell does Valvoline have to do with this? Is that supposed to discredit dealers or manufacturers since you seem to be using both? So you are going on record as saying that dealers will recommend a fuel that will destroy the customers engines simply to increase sales?

3. "As far as timing per altitude, most new cars have comp controlled timing, that adjusts with sensors. But in the case of a distributor ignition...Well, lets just say i wouldnt ask someone on a message board, there are plenty of credible websites and other sources of info that can be tapped for such an important issue."

No kidding, computer controlled timing........:rolleyes: With regard to distributor ignitions you provided no information at all except go somewhere else, how helpful.

In short I would suggest you are a much better dancer than I, perhaps a change in profession is in order?

[shane]

what an interesting first thread i chose!!!
wow!!! way to go oldster!!!

[oldster]

Originally posted by shane
what an interesting first thread i chose!!!
wow!!! way to go oldster!!!

If you have any qualms or questions please contact a local knowledgable mechanic. Good luck and happy motoring. :)

[shane]

what i was most amused by was the whole thing about the air being thicker at higher altitudes!!! :rofl: has there been a reverse in the laws of physics that i am not aware of??? :confused:

[GMSeasonedTech]

Quote-"Am I supposed to read between the lines here, what the hell does Valvoline have to do with this? Is that supposed to discredit dealers or manufacturers since you seem to be using both? So you are going on record as saying that dealers will recommend a fuel that will destroy the customers engines simply to increase sales?"- posted by oldster

How much more obvious do I have to make it. Yes thats exactly what Im saying. Sheesh. okay everyone get out a pen and paper, Oldster, get out your crayon and paper. A dealer would do anything for a sale, especially nowadays with gas prices. Its the perfect avenue.

Quote-"How helpful, tells us lots about the effects of atltitude on fuel distribution, effective compression ratios and timing."

Your missing my point. I wouldnt use 85 octane at any altitude. Not in Ohio, Not in Colorado, Not driving around in the cockpit of a 747 Jet at 30,000 feet. To put this into terms you can understand, 85 octane= too low for ANY altitude.

Quote-"
Am I supposed to read between the lines here, what the hell does Valvoline have to do with this? Is that supposed to discredit dealers or manufacturers since you seem to be using both? So you are going on record as saying that dealers will recommend a fuel that will destroy the customers engines simply to increase sales?"-posted by my good buddy oldster.

Yes im discrediting what the dealer/manu tells you. Not always but in this case Yes. They are wrong. Again, in big letters for you now oldster "DEALER WRONG-85 TOO LOW OCTANE" But hey shane, if you want to sell me your engine for a couple bucks every time you fill up, ill gladly buy it. cheapass.

You keep referring to me as if I ever said anything about high altitude fuel distribution in the first place. And your absolutely correct, that is something I would have to look into. I have never run into that situation, but I have confidence that if one of my customers came to me from colorado with a fuel/timing problem, and needed service, I could do the proper wrenching on his vehicle to keep it at optimal performance without causing internal damage to his engine.

Bottom line good ole buddy is this, I frequent this board and havent really been inclined to post until I saw your "question about elevation and fuel dist." and since ive always had this thing about know-it-alls that know less than they think, well, i decided to post and see what you were about. And Im still not sure your anything more than a 15 year old with a Haynes manual on his lap using his daddy's handle.

-GM-

[Celica NZ]

*ding ding* next round.

Oh, and could you use the http://www.newcelica.org/forums/images/quote.gif facility it makes the cut and thrust easier to follow.

[shane]

chill out buddy... you dont even know me... how can you say i am a cheap ass??? i am currently unemployed and still i would never use less than 87oct anywhere period... no matter how high the gas prices get... so no you cant have my engine!!!
oh and i never refered to you in any of my posts so why the hell are you attacking me??? :mad:

[oldster]

Originally posted by GMSeasonedTech

And Im still not sure your anything more than a 15 year old with a Haynes manual on his lap using his daddy's handle.

-GM-


Based on your responses my age is not the only thing unclear to you. The following quote pretty much sums up your expertise and qualifications:

"Your missing my point. I wouldnt use 85 octane at any altitude. Not in Ohio, Not in Colorado, Not driving around in the cockpit of a 747 Jet at 30,000 feet. To put this into terms you can understand, 85 octane= too low for ANY altitude."

Millions of gallons of 85 octane gas are consumed in the mountains states each year. Surely with your expertise you can show me some statistics pointing out the abnormally high warranty cost for engine replacements in the region. Wait, the warranty cost would start exceeding the margins made by lying to the customers and selling more cars. Oh crap, what do we do now? Help us GMseasonalTech what now? :rolleyes:

PS - I certainly don't claim to know it all but I am familiar with some basics, you on the other hand.................

[shanetrain]

I appreciate your responses, just 1 other question. As I mentioned before, I also have 2 other vehicles. Do you feel it would be ok to run 85 in them as well. Both of them also reccomend 87 as well.

[GMSeasonedTech]

Millions of gallons of 87 octane gas are consumed in the mountains states each year. Surely with your expertise you can show me some statistics pointing out the abnormally high warranty cost for engine replacements in the region. Wait, the warranty cost would start exceeding the margins made by lying to the customers and selling more cars. Oh crap, what do we do now? Help us GMseasonalTech what now? -Posted by Oldster

-Well oldster, as the quote indicates you are correct. Millions of gallons of 87 octane gas are consumed each year. The only problem is that I was talking about 85 octane gas. GAWD.

~GM~

-Shane- You came on praising oldster, hence the dig at you, dont take it personal bro.

[Acilec]

Ok, guys, please be mindful, no flaming or the thread will be closed.

Thanks.

[F22-Raptor]

Wow look what we started:) Ok Oldster I did some heavy digging last night into physics and such and you are partially right. Based Just on octane ratings you might be able to get away with using 85. Due to atmospheric pressure you can go down 2 octane ratings for every -1 you have in air/fuel ratio.Depending on what the car is set at the factory. However the same article I read that in also said you had to take into account driving styles the brand of gas used (yes they are different :)) and other things. So in summary yes you can probably get away with it. Yes Toyota has legal right to say you destroyed your own engine with low octane gas if it ever happens-not saying it will lest we go into heated battle :) just saying it could. By the way the math behind this is as follows:

Traditionally, the greatest tendency to knock was near 13.5:1 air-fuel
ratio, but was very engine specific. Modern engines, with engine management
systems, now have their maximum octane requirement near to 14.5:1. For a
given engine using gasoline, the relationship between thermal efficiency,
air-fuel ratio, and power is complex. Stoichiometric combustion ( air-fuel
ratio = 14.7:1 for a typical non-oxygenated gasoline ) is neither maximum
power - which occurs around air-fuel 12-13:1 (Rich), nor maximum thermal
efficiency - which occurs around air-fuel 16-18:1 (Lean). The air-fuel ratio
is controlled at part throttle by a closed loop system using the oxygen sensor
in the exhaust. Conventionally, enrichment for maximum power air-fuel ratio
is used during full throttle operation to reduce knocking while providing
better driveability [38]. An average increase of 2 (R+M)/2 ON is required
for each 1.0 increase (leaning) of the air-fuel ratio [111]. If the mixture
is weakened, the flame speed is reduced, consequently less heat is converted
to mechanical energy, leaving heat in the cylinder walls and head,
potentially inducing knock. It is possible to weaken the mixture sufficiently
that the flame is still present when the inlet valve opens again, resulting
in backfiring.

[F22-Raptor]

Naw Acilec we are all learning here Oldster teaching me some stuff bout high altitude and sich. :)

[oldster]

Originally posted by shanetrain
I appreciate your responses, just 1 other question. As I mentioned before, I also have 2 other vehicles. Do you feel it would be ok to run 85 in them as well. Both of them also reccomend 87 as well.

The same rules would apply to any engine requiring 87 octane. Be aware when you first try it though. Whether it is an automatic or manual just get it into high gear and find somewhere to lug it down, slight hill etc, that condition will be the most pronounced. If you experience pinging you will need to bump up to the next grade. As Raptor said, you can get crap gas anywhere so be careful (at any altitude I might add).

[oldster]

Originally posted by GMSeasonedTech
-Posted by Oldster

-Well oldster, as the quote indicates you are correct. Millions of gallons of 87 octane gas are consumed each year. The only problem is that I was talking about 85 octane gas. GAWD.

~GM~

-Shane- You came on praising oldster, hence the dig at you, dont take it personal bro.

My bad, that obviously should have been 85 octane..........sorry for the confusion, will edit the post now.

[Acilec]

Originally posted by F22-Raptor
Naw Acilec we are all learning here Oldster teaching me some stuff bout high altitude and sich. :)

I gotcha, but there was some tension earlier :)

Interesting info though guys!

[GMSeasonedTech]

The same rules would apply to any engine requiring 87 octane. Be aware when you first try it though. Whether it is an automatic or manual just get it into high gear and find somewhere to lug it down, slight hill etc, that condition will be the most pronounced. If you experience pinging you will need to bump up to the next grade. As Raptor said, you can get crap gas anywhere so be careful (at any altitude I might add).
-Posted by oldster

I agree with you there, oldster. Some people believe a slight ping means that your engine is tuned properly, which is IMO terribly wrong. It has been said, that for every hour that your engine runs with a low octane ping, it takes one year off of the life of the engine. ~GM~

[F35-JSF]

Interesting info Gm tech, Thanks!

BTW:
Tomorrow........ http://www.phpbb.com/styles/gallery/albums/Smiles/General_Smiles/new_snipersmilie.gif