The minimum octane rating gasoline that should be used in my vehicle

The way understand it is that modern engine managment systems control the ignition timing by advancing the timeing to the point of spark knock then retard it slightly as to not cause damage to the engine.The vehicles ecu is doing this many times a second.Like most all things that the ecu monitors and controls in todays cars it is for reducing emissions.The more spark advance the more power(to a certain point).The harder the piston is pushed down the less fuel needed for a given unit of work.Or something like that.

 

In the altitude of Albuquerque, it seems that they use 86 octane for regular, 88 for mid-range and 90 for premium. I have used mid range for the last few years, but I filled up with regular on a tank not that long ago, and I cannot tell any difference...is 86 acceptable?

 

i use mid grade(89).lasts longer then regular, and premimum is to expensive.

 

out here in colorado we have 85 octane. been using that on my brand new 2011 v6 for three tankfulls. i live at 7500 ft and most of my driving takes me higher and higher and higher. Just hit $3.06 for 85 octane

 

ok i just found this thread and i feel like i should put my 2 cents in for anyone that is still sub'd or looks at it in the future.... fuel prices recently spiked as we all know, here in NEPA, were paying $3.59(87) $3.69(91) and $3.79(93)

So here are all of my culculations and inputs..

First off, in ANY 'small engine', (i.e. Lawnmower, weedwacker, ATV, etc) if the fuel in your area contains ANY bit of Ethanol, never use anything less than 93 octane. Ethanol breaks down and leaves deposits in the carburator and makes it run like crap or not run at all (seen this in my 400EX AND my brand new pressure washer, also in my buddies lawnmower) when i fill up a 5 gallon jug with 93 i always add a few ounces of Sta-Bil Ethanol treatment. This has helped everything run way better.

Next, in my Tacoma...
87 octane w/ 10% ethanol, 17.5 Avg MPG
91 octane, 18.9 MPG

SAME driving styles, same roads/speeds everyday so please no (Negative) input stating im probably doing different things.
With these statistics, ive calculated how much it cost per gallon.
I am saving 1 Cent PER MILE
Doesnt seem like much, but in 100 Miles thats $1.
So in each fill up thats $3
I Avg 20-22K miles per year, you will save an estimated $200.
with the economy these days.. ill take 1 Cent per mile!!!!!!

(Edited)

 

I read in a owner's manual for a 1986 Caprice and in a manual for a 2000 Impala (it's old, but the car had electronic spark control not much different than any Tacoma) saying that higher the altitude the lower the octane reading you can use, but I see a pattern that the gas at say, LA has a higher minimum octane rating than say here at the 5000 ft altitude of Albuquerque, NM. From what I figure that the higher air densities require higher octane levels to prevent knock same for any higher compression or supercharged car. This makes sense from what the manuals are saying.

 

Keeping tight records using fuelly I noticed this, using 87 engien runs a bit ruff, under load or highway driving it prob runs like its meant to. Mpgs averaged fro 17 to 19. Using 89 smoothed out at idle and highway cruising speeds and yielded same mpg, next I mooved to 91, same smoothness with 87 but deff felt like I lost bottom end power but gained top end. 3.25 k and up when u punch it out it's almost like I add a power added or somthing. My mpgs also averaged from 18 to 22. Next I tried 93, deff increese in top end but mpg stayed around the same.
This was all don using shell gas the same station using the same pump in southern ny. Over a 4 month span. When between octanes I ran the truck till the light came on and didn't record my results till the next fill up.

 

Note that the key is the altitude. Those of you who live at sea level, don't try 85 octane

 

Interesting comments. I have a 2014 DC. When I first purchased it I was running high octane. Then I switched to low octane and I swear the truck runs better. Some factors to consider.... I'm at sea level, truck only has 1,200 miles on it, I'm in CA.

 

My 2014 Tacoma manual says DO NOT use 91 Octane.

 

My 2014 Tacoma manual says DO NOT use 91 Octane

 

wut

Post a pic

 

Sorry man, i lied...I hate it when that happens. It just says to research 91 or higher. I have a reading lesson tomorrow.

 

Just got back from a road trip in Utah. Found it odd that they sell 85 octane. My first tank in Utah I got so excited by the cheap price of gas 3.39 for the reg unleaded and I was so sleep deprived that I filled up using 85. Thankfully had thrown in a Techron Fuel Injector cleaner (not sure if it helps with the low octane) with that tank so I feel better about using sub-par octane in my 2013. Just curious if any utah tacoma drivers actually use the 85 octane.

 

Yes, no need for higher at altitude.

 

oh boy... I have a 2014 DCSB and love it. After getting horrible gas mileage for the for 20k miles I thought would look up what the issue may be. Turns out the guy that sold me the truck may have been full of $h!t. When I asked what kind of gas I needed he said 'regular'. This was news to my ears since my 6cyl Subaru took premium... uh oh...

Here is Colorado 'regular' is 85, even at Costco...

So, it seems that after reading all of this it seems that I have been using the wrong gas...

Is that correct?

Also, Costco doesn't carry mid-grade, should I just use premium?

 

These trucks are set up for 87. If you put anything higher than that in the computer adjusts for it and does something to the timing. That's what the service dept. told me. It doesn't hurt anything to go with a higher octane but you're wasting money.

 

Since you live at 5000+ ft 85 is the same as 87 at low altitude. Colorado AAA gives an explanation:

"Colorado is among a group of states where regular unleaded gasoline has a lower octane level (85) than is normal elsewhere in the country (87)."