Is 91 octane really over kill on a 3rd gen?

[Ironman707]

So I've read a few threads and posts that 91 octane isn't required on the 3rd gen. I have a 02 and I've been running it with 91 octane since I got it. And honestly I've ran all my previous cars with 91 octane. Specially my 04 RSX type S that I've had brand new. Mainly I run it because I heard it's the best gas for your engine, and I've never had any issues with my RSX

So is it true that it could be overkill to run such rich fuel?? I know you're suppose to run 91 on a super charger engine but mine is completely stock at the moment

Anyone care to elaborate if it's true?

My 91 octane babies :boink:

 

[amalik]

If you aren't running a Supercharger or Turbocharger, it is overkill, yes.

The octane rating is only a measure of when the gasoline will detonate. Putting 89 for example in an engine that requires 91 means it will knock/pre-detonate, which is bad. The 4runner engine compression ratios weren't designed for 91. i.e, you won't pre-detonate/knock with 89 without paying extra for 91.

https://en.wikipedia.org/wiki/Octane_rating

You are simply wasting $ and nothing more. But I'm sure the oil companies aren't complaining about you.

http://www.statista.com/statistics/272710/top-10-oil-and-gas-companies-worldwide-based-on-revenue/

If you want a 'feel good' measure, throw in some BG44K or fuel cleaner type of deal instead of wasting money on gas.

 

[RedSled]

I agree with the above.

 

[kpinthebay]

It's an ingenious marketing scheme by calling 87 "Regular" and 91 "Premium" or "Supreme"

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[LittleCaesar]

IMHO not overkill at all. I used to run 93 in mine every other time while on trips to DC anf back and it ran smoother than when using 87. Now its either 91 or 93. Let your wallet decide for you.

I have seen people run 89 and below in cars that requires premium fuel. Not good. The car would shake, not idle well and even a knock sensor may have to be replaced.

By the way my Acura Vigor, which required premium unleaded, had a lower compression ratio than the 5vz.....

 

[PWD4R]

IMHO not overkill at all. I used to run 93 in mine every other time while on trips to DC anf back and it ran smoother than when using 87. Now its either 91 or 93. Let your wallet decide for you.

I have seen people run 89 and below in cars that requires premium fuel. Not good. The car would shake, not idle well and even a knock sensor may have to be replaced.

By the way my Acura Vigor, which required premium unleaded, had a lower compression ratio than the 5vz.....

I think you fell in to the marketing scheme. Even a corvette will run fine on 87 octane. Now, those engines can run hot enough to burn the higher octane fuels correctly and they will be more peppy with 93 octane but 87 won't mess anything up.

For normal vehicles 87 is 100% fine. I would be willing to bet my paycheck you won't see a 1% difference in fuel economy from 87 to 93--if anything you'll get worse mileage because your vehicle can't burn the fuel hot enough to make it work right. There are tons and tons of stories on fuel ratings and they are unnecessary for almost every vehicle. Even if the vehicle says "premium fuel only" that isn't necessary.
The 2005-2012 Nissan Pathfinder is "recommended" for premium fuel but it's the exactly same VQ40DE found in the xterra that doesn't require it. It's pure marketing.


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[Scramble]

I think you fell in to the marketing scheme. Even a corvette will run fine on 87 octane. Now, those engines can run hot enough to burn the higher octane fuels correctly and they will be more peppy with 93 octane but 87 won't mess anything up.

For normal vehicles 87 is 100% fine. I would be willing to bet my paycheck you won't see a 1% difference in fuel economy from 87 to 93--if anything you'll get worse mileage because your vehicle can't burn the fuel hot enough to make it work right. There are tons and tons of stories on fuel ratings and they are unnecessary for almost every vehicle. Even if the vehicle says "premium fuel only" that isn't necessary.
The 2005-2012 Nissan Pathfinder "requires" premium fuel but it's the exactly same VQ40DE found in the xterra that doesn't require it. It's pure marketing.


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You just lost your paycheck...

 

[PWD4R]

No. I have done the differences with all the vehicles I have owned and there are no improvements.
And also hours of research and news stories.

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[LittleCaesar]

Not to be obtuse, for the subject is always a point of contention for those who do or don't use premium octane, but how is it a marketing scheme?

 

[T5RUNNER]

You just lost your paycheck...

High compression engines can be more efficient but require high octane to do it. Our trucks do not have high compression engines. If you have been putting high octane in a car that doesn't require it, you have been losing a little off of all of your paychecks.

Not to be obtuse, for the subject is always a point of contention for those who do or don't use premium octane, but how is it a marketing scheme?

Because "premium" makes it sound like it is "better", in reality it's just different.

It would be like calling 0w20 motor oil "regular" and 10w30 "premium".

 

[Scramble]

High compression engines can be more efficient but require high octane to do it. Our trucks do not have high compression engines. If you have been putting high octane in a car that doesn't require it, you have been losing a little off of all of your paychecks.



Because "premium" makes it sound like it is "better", in reality it's just different.

It would be like calling 0w20 motor oil "regular" and 10w30 "premium".

I have never put anything other than 87 in my 4runner. So to the OP I say yes it's a waste of money.

PWD said 100% of normal cars don't need it & it's marketing. That's hog wash, I though it was common knowledge that putting in a lower octane than recommended by the manufacturer will cause rough idling/knocking etc. My last 7 Caddy's wouldn't run on anything less than 91 & they were normal, not CTS-V's or anything although I wish I could afford one.

 

[PWD4R]

Just because it says use premium doesn't mean you need to and nothing will happen. And I didn't say 100% don't need it.
If it's recommended then it's a waste if it's required then it needs it more often than not but what the confusion is with people seeing recommended and thinking it's required

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[Collkid]

I use to deliver Pizza's in a 1994 Acura Integra GSR.

Using regular I would get about 21 MPG.
With premium, I would get 26 MPG.


All that to say, it does make a difference.

However, I don't plan on using it in the 4runner. Simple engine.

 

[Cree]

In a 4Runner, it's overkill unless you're boosted. That's been covered.

To the dumb dumb that says it doesn't make a difference, tell ya what. Come ride my Harley and say that. 87 pings like a *****, so bad in fact that I carry octane boost with me just in case I have no choice but to run 87 (think Casey's General or similar podunk stations). 91 or better, no problems.

Compression is not the only determining factor when it comes to octane rating. Your timing settings will also play into it. So a you could have two engines that are the same compression require 2 different types of fuel due to the timing curve. Now, that's not as prevalent as it used to be since OBDII came around with knock sensors and more advanced management systems. But not every vehicle is equipped with them or even monitor them under normal driving conditions.

Bottom line, when you have a question like this, do as much of your own research as you can, and remember there's going to be at least two people that reply every time with really long replies that may or may not be full of misinformation.

 

[UnderFire]

Ran nothing but premium shell from the same station for months in my runner, then switched back to 89 from the exact same station for another few months, zero difference in MPG, the second post is right.

 

[JtuckerSvces]

So I've read a few threads and posts that 91 octane isn't required on the 3rd gen. I have a 02 and I've been running it with 91 octane since I got it. And honestly I've ran all my previous cars with 91 octane. Specially my 04 RSX type S that I've had brand new. Mainly I run it because I heard it's the best gas for your engine, and I've never had any issues with my RSX

So is it true that it could be overkill to run such rich fuel?? I know you're suppose to run 91 on a super charger engine but mine is completely stock at the moment

Anyone care to elaborate if it's true?

My 91 octane babies :boink:

I like premium, It runs smoother and plugs stay new longer. But any gas is better than no gas.

 

[Ironman707]

I like premium, It runs smoother and plugs stay new longer. But any gas is better than no gas.

That's why I like premium too... I thought that running premium would keep my engine at top notch. I'd like to keep it that way but if it's not true then maybe I'll run 87 until I slap on a super charger

 

[Roc Doc]

There are many factors that contribute to the octane requirement of an engine. Obviously compression ratio, but also piston top and combustion chamber design can have "hot-spots" that can contribute to pre-ignition (knock). Also temperature and altitude can make for more lean or rich conditions. With modern ECU's the ignition timing and fuel mix can compensate for most of these variables. In a "premium fuel only" engine, yes most will run just fine on 87, although maybe not at peak power output, (not noticeable in most driving conditions). Towing at the 5k limit, with four fat dudes and all their fishing gear (ice chest full of beer), up a mountain on a hot day...you're probably going to want premium.

Me? I run regular, but if I get a SC then I'll run premium.

 

[T5RUNNER]

Just because it says use premium doesn't mean you need to and nothing will happen. And I didn't say 100% don't need it.
If it's recommended then it's a waste if it's required then it needs it more often than not but what the confusion is with people seeing recommended and thinking it's required

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This post will confuse people though, modern engines that are designed for high octane say recommended because they will protect themselves by retarding ignition timing when you use lower octane gas. This will prevent damage but will reduce both power and mpg. The 4Runner is not designed for high octane so it makes no difference for us.

Also, your previous post about high octane "not burning hot enough" is not how it works.

 

[BWJones]

That 4Runner always ran premium. Plugs seems to last longer and look better when they were swapped out.