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Discussion Starter · #1 ·
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
 

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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.
 

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Discussion Starter · #3 ·
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.
 

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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.
 

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shanetrain said:
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.
 

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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.
 

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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 :)
 

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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'?
 

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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.
 

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Re: Re: question about octane ratings

oldster said:


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.
 

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F22-Raptor said:
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.
 

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oldster said:


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.
 

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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?
 

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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~
 
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