LandsEnd

Is it okay to mix half 87 octane with half 93 octane to get 90 octane? I have used 89 octane since I have had the car. My question is will it basically mix properly inside the gas tank to make 90 octane without messing the computer up? I would like to do this everytime I fill the tank up from now on just because I'm getting it for the SAME PRICE as 89, and its closer to that reccomended 91 octane rating.

I know I can go 89, and 93 for 91 (ideal octane level for POWER), but I'm looking at PRICE here, so answer my above question please.

lostru

If you really want too it wont hurt anything and should (MIX). With my driving habits I use 89 most of the time with no spark knock. I am new to the MAX but usually it only takes a tank full for a computer to fully readjust and run fine.

philoforlife

That is a lot of work for one octane level, and hardly worth it. But yes, you can do it without problems.

Joshua

tubells

thats what the gas stations do to get 89 oct anyway.... mix 91 and 87!! (at least here in Toronto)

LandsEnd

Don't have 91 here.

lightonthehill

LandsEnd - Since the Maxima performs perfectly well for almost any style of driving with 87 octane, having to reenter your credit card and restart the pump twice for each fillup just to gain one octane from 89 to 90 seems way over the top. Especially when considering:

1. Gas may be sold as 'octane X', but in reality will always be just a tad higher or lower; just as everything else in life, the refineries are not perfect.

2. With pumps that feed all grades through one hose, you will always start out with a 'hoseful' of unknown octane.

3. Not knowing EXACTLY how many gallons the refill is going to take, you either have to estimate and be somewhere near 50-50, else stop short of filling when you have entered the same amount of the second octane as you did the first.

4. Many robberies and carjackings occur at gas stations. By taking the time to mix octanes, you are increasing the time span in which you are vulnerable. I won't even gas up at night or at a station where there aren't a lot of people unless absolutely necessary.

5. Nissan's recommendation of 91 is intended to give the absolute maximum performance in extreme situations, such as running a timed quarter mile. Despite daily claims to the contrary on the ORG, the difference in everyday driving will not be noticable. Countless tests over many decades always prove that higher octane does NOT change gas mileage at all. The only benefit for normal driving is that higher octane may tend to leave the engine somewhat cleaner.

But the difference between 89 and 90? I can't find a valid reason to put forth any effort to make that change.

I really admire your efforts to 'do the right thing' by your Maxima, but I would reccommend against this idea.

SilverMax_04

With the US Government's (and some state governments too) requirement for so many slightly different blends of gasoline -- there are no more pipeline and/or terminal tanks set aside for mid-grade gasoline. When loading a tank truck to take gasoline to the gas station, the mid-grade is splash blended into the tank truck using regular and premium -- plus any ethanol that may be required by regulations. So there is no problem with you splash blending into your car's gas tank.

light gives you some good advice in his post, above.

Here in Colorado (most of my driving is done at or above 6 K feet in elevation). I only burn 85 octane regular in my Max -- with no problems. One reason I have no problems at this elevation is that 85 octane at 6 K feet performs like 91 octane at sea level -- provided you don't have a turbo-charger on the engine.

But when I drive east I always burn the cheapest grade of gasoline -- which is usually (but not always) 87 octane regular. I never have any problems burning 87 octane -- but then I don't normally floor my Max (WOT) or call for maximum performance. If I were racing my Max all of the time, I would be using premium (when I leave the mountains). But since I don't -- I don't.

There are many misconceptions about gasoline octane, and I tried to clear some of them up in this older thread from this site.

Well folks, it looks like the site has completely dropped this thread on gasoline octane from the site. The link that I had saved to get to this thread no longer works (it did work about 4 months ago). Luckily, I have kept a copy of all of my posts, so that I could re-post this information -- without having to recreate all of it.

LandsEnd

Your right it is over the top I guess ESPECIALLY if gas mileage is the same. I'll stick with my 89. You talked me out of it. Little confused here though. They sell only 87, 89, and 93 where I live no 91. Why wouldn't the mix of 87, and 93 be 90 instead of 89? That would be easier to get a 50/50 mixture, or is it really 90, and they call it 89 to be safe on their side.

SilverMax_04

Octane is a "wierd animal" and most times the numbers don't exactly add up in a linial fashion. Also there are a number of instances where there is some "octane giveaway" versus the numbers posted on the pump so that all of the gasoline specs are met when the product is blended -- either at the refinery or in the tank truck.

But you are basically correct that a 50/50 blend of 87 and 93 should essentially get you 90. But when they blend 89 octane mid-grade into a tank truck they don't do exactly a 50/50 blend. Here regular is 85 octane and premium is 91 octane and the mid-grade is 89 octane and again they do not do a 50/50 blend (which would normally get you 88 octane).

pmohr

iTrader: (26)

http://forums.maxima.org/showthread.php?t=537445

SilverMax_04

Thanks to phmor, it will not be necessary to repost the information that I previouly posted on "Gasoline Octane Number and what it means." It is all still here at:

http://forums.maxima.org/oldthread.p...6&goto=newpost

Check out the listing in my first post on the different sub-topics about octane.

ghostrider17

iTrader: (6)

At sea level (for clarification) I burned a tank of 89 Octane ONCE while on a roadtrip. It ran okay on the hwy, but I got knocking immediately once I resumed my city driving habits on the same gas.
Oh, and my gas mileage was lower too, by maybe 10%.

I won't EVER do that again. Premium fuel is on average .10 more than midgrade?? So, you're talking $1.75 more per fill up??
Cheap insurance if you ask me.
And I DO drive at WOT, and I can tell a noticeable difference between mid and super~!

gr

ROCKART

iTrader: (23)

i never really get a straight answer about octane. i drove volvos and a 1993 maxima on the cheapest gas i could buy for 6 years with NO PROBLEMS. no knocking, mpg was fine, etc. then i get a 96 and 97 GLE and find out that not only do you all obsess about high octane, but it also says in the owners manual to use high grade gas......ive tried both since and see no difference in MPG or performance. i still use high octane but ive been asking around.


my uncle actually used to work with aeronautical combustion engineers at an airport in the 70s. apparently when he was my age he was also right in the middle of the high octane vs. low octane argument. he did a fair amount of research into it and ended up talking to one of these fuel prodigies who said that high octane, 91, would yield no cleaner or better results than low octane, 87, in the engine of an automobile. only in high performance engines such as that of a race car or airplane - where rate of burn is highly sensitive - would you see a difference.

he since has done a lot of research about it and shared it all with me last month when i went up to NC to see him.

the way he explained it was this. when the valve fills up with the air/gas mixture and ignites, it will burn much smoother with higher octane gas. the composition of the gas is designed to be consistant in combustion - meaning it will burn at a constant and static rate from one end to the other. this, as it is, may result in SLIGHTLY reduced horsepower, because the piston is not firing as violently.
lower octane gas does the opposite. it ignites rapidly and progressively, which causes the occasional engine knock. this engine "knock" is the very reason people use 91 in the first place. lower octane gas, especially in engines as simplistic as ours, will actually yeild no damaging effects as far as the knocking goes because our cars are designed to deaden this knock (the piston hitting the valve ?). it does happen occasionally, but not enough to warrant putting an extra 4 bux into your tank everytime you fill...

i used to think the octane levels had to do with impurities in the fuel, probably from those shell commericals with the tiger jumping out of the hood, but i was wrong. they are both filtered and cleaned equally as well due to the restrictions of US energy commissions.

basically, he calls me an idiot for filling my car with high octane

im still putting 91 or 93 in my maxima but its something i do think about when pressing that big yellow button at the gas station.

ghostrider17

iTrader: (6)

Good info!
Something that hasn't been touched-on is additive packages.
I've always been of the impression that premium fuels had more detergent in them as well -- but I have no proof of this....

Again - I'll STILL stick with the premium in my car.

gr

SilverMax_04

That is because there are no "straight answers about octane." Octane is not exactly linear -- but close enough that you can frequently treat it that way. I worked for an oil company for 35 years, so I know something about the subject.

There are also many misconseptions about octane that people know are "true" -- so they refuse to listen to the real truth. I have imparted much of what I know and understand about octane in my posts on the thread listed below. Many on this site refuse to believe what I have posted -- so be it.

http://forums.maxima.org/oldthread.p...6&goto=newpost

Well the truth is that you may or may not be an idiot -- depending on your driving style. If you do frequent and hard accelration (or race at WOT) I would stick with premium. If you don't, then you should try a couple of tanks of mid grade gasoline. If these work OK for you and you don't hear any knocking (or see a drop in gas mileage), you could then try a couple of tanks of regular (with the same stipulations). Also, each engine is slightly different, so while my VQ may perform properly on 87 octane at sea level, yours may require 89 or even 91 octane to do the same.

There is also the scientific idea that, so long as you don't get engine knocking, you should get better gas mileage burning regular than burning premium. The basis for this belief is that premium octane reduces the tendency for gasoline to burn (pre-ignite) and so regular gasoline should burn better than premium. But with the VQ engine having a knock sensor that retards the spark to prevent knocking, this would only give the same or better mileage so long as there is no retarding of the spark when burning regular.

Also, remember that the 04 Owners Manual (and as I understand many other Max years) says that it is OK to use regular gasoline -- provided you don't expect maximum performance from the engine.

ghost: For many years oil companies put a higher additive treat rate in their premium gasoline. When the oil business became so marginal (for profits) in the 1990s, most oil companies went to putting the minimum government mandated treat rate in all of their grades of gasoline. I believe they are still doing this today; but being retired, can't be certain about that. I do know that the profit margin for premium gasoline has declined so that we are now seeing more and more oil companies charging more than the historic 10 cent-per-gallon difference for each higher octane grade of gasoline. I expect that trend will continue until the difference is more likely to be 15 cents per gallon or more.

lightonthehill

SilverMax_04 - Your last post agrees not only with what I have read in technical manuals/mags (and some not so technical such as Consumer Reports), but what I have always experienced when checking the mpg on long freeway trips using different octanes.

I realize there will always be those who feel they are getting better mpg with higher octanes, but every controlled test continues to show that is not true. I think the misguided opinions either result from tests that were not totally controlled (such as run on only a tank or two, or not on the same exact trip with the same exact conditions), or from the desire of the individual that the more expensive gas should show a measurable benefit, or from the normal desire of many Maxima owners to do something a little 'extra' for their Maxima.

I continue to use 89 octane, even though I understand my Maxima performs the same mpg-wise and virtually the same performance-wise with 87 octane. I just have that unexplainable urge to do something a little 'extra' for my Maxima.

SilverMax_04

Thanks light! You are correct. So many times posters to many of my points about octane would say: "only the best for my baby !"

My point continues to be that if you race or do frequent WOT, then Premium gasoline is the best. But if you don't, then a lower octane gasoline may be the best. Only you can decide what is best, but you sould make that decision based of fact and not emotion.

ghostrider17

iTrader: (6)

Daddy likee him some WOT~!
I'm stickin' with the super.
gr

ROCKART

iTrader: (23)

lot of good info in this thread.

thank you to silvermax04 and lightonthehill.