From Vincent Ciulla,
Your Guide to Auto Repair.
http://autorepair.about.com/cs/gener.../aa062300a.htm

Are you tempted to buy a high-octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner’s manual recommends offers absolutely no benefit. It won’t make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner’s manual.

The only time you might need to switch to a higher octane level is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars.

Unless your engine is knocking, buying higher octane gasoline is a waste of money, too.

Premium gas costs .15 to .20 cents per gallon more than regular. That can add up to $100.00 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher-octane gas than they need.

What Are Octane Ratings?

Octane ratings measure a gasoline’s ability to resist engine knock, a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders. Most gas stations offer three octane grades: regular, usually 87 octane, mid-grade, usually 89 octane and premium, usually 92 or 93. The ratings must be posted on bright yellow stickers on each gasoline pump.

What’s The Right Octane Level For Your Car?

Check your owner’s manual to determine the right octane level for your car. Regular octane is recommended for most cars. However, some cars with high compression engines, like sports cars and certain luxury cars, need mid-grade or premium gasoline to prevent knock.


How Can You Tell If You’re Using The Right Octane Level?

Listen to your car’s engine. If it doesn’t knock when you use the recommended octane, you’re using the right grade of gasoline.

Will Higher Octane Gasoline Clean Your Engine Better?

As a rule, high-octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car’s engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.

Should You Ever Switch To A Higher Octane Gasoline?

A few car engines may knock or ping — even if you use the recommended octane. If this happens, try switching to the next highest octane grade. In many cases, switching to the mid-grade or premium-grade gasoline will eliminate the knock. If the knocking or pinging continues after one or two fill-ups, you may need a tune-up or some other repair. After that work is done, go back to the lowest octane grade at which your engine runs without knocking.

Is Knocking Harmful?

Occasional light knocking or pinging won’t harm your engine, and doesn’t indicate a need for higher octane. But don’t ignore severe knocking. A heavy or persistent knock can lead to engine damage.

Is All "Premium" Or "Regular" Gasoline The Same?

The octane rating of gasoline marked "premium" or "regular" is not consistent across the country. One state may require a minimum octane rating of 92 for all premium gasoline, while another may allow 90 octane to be called premium. To make sure you know what you’re buying, check the octane rating on the yellow sticker on the gas pump instead of relying on the name "premium" or "regular."

As a follow up 20/20 last week did a 10 ten myths and higher octane fuel was number 5 on the list with some of the top Master Mechanics and NASCAR crews and driers backing the above claim.

Last month, the Discovery Channel Show Myth Busters came to the exact same conclusion

Last and most important piece of advice as stated above:

“Using a higher octane gasoline than your owner’s manual recommends offers absolutely no benefit”.

For the 6th gen max "sorry only owners manual I have" the manual states "for improved vehicle peformance NISSAN recommends the use of unleaded premium gasoline with an octane rating of at least 91 AKI number (Research Octane number 96).

Aftermarket fuel Additives

Nissan does not recommend the use of any fuel additive (for example, fuel injector cleaner, octane boost, intake valve deposit removers, etc) All have been known to contain active solvents or similar ingredients that can be HARMFUL to the fuel system or engine...

FYI only, use it or loose it...

 

mad good info !!

luigi

 

i wish i could put 87 in my car..... damn 3.5 with cams and no cat and all that nice stuff..... i prefer to run 112 lol but at 7.25 a gallon its a little pricey hahaha... good info chern!

 

Why should I listen to the guy when there are 100 others saying different things? It's simple, we have a pretty high compression engine and using 91+ octane is optimal for compression ratios of 10.0:1 and higher. If you're engine runs with 87 octane, good for you. Just wait for the weather to get above 90 and make a few hard runs, the car will knock like a **** most likely. Hell, I've been in cars that had 87 octane and then rode in them with 93 octane. Every single time the car runs "better". Hell my parents always used 87 octane in their car cause it was recommended for the cars. I then put 93 in without telling them and they pointed out the cars run better. This premium vs regular BS is so old I don't even see why it has to be brough up again.

 

Because with new Org members signing up daily, what's old to you is new to them, plus new info and experts are chimming in that support the myths of high octane verse regular. If you feel you have reached your learning peak on this subject, feel free to skip this thread...

 

for the extra 100 bux a year i would be saving for a piece of mind...its worth it to just put in the premium. and its not like nissan would make it so u have to put 91 in because they are tryin to make money. its all for the benefit of the engine. the extra dollar or 2 i spend filling up is worth it to my engine and my pocket. after all i have 153k on this bad boy and shes lovin it

 

You didn't mention what car your parents drive. If 93 octane runs better in a car that recommends 87, there is probably something wrong like carbon buildup, hot plugs, or some other underlying issue.

The addage of using the lowest octane rating that doesn't ping is B.S. Most if not all modern engines have knock sensors that can detect a ping before you can. In response, the ECU will retard the timing and if necessary dump more fuel into the cylinder causing it to run rich.

Unless you're doing stuff like advancing the timing, F/I, or high temperature operation (100deg.+), there's no reason to use a higher octane than the manufacturer recommends.

 

kinda OFF topic but what you guys think about mixing of gas?

 

Excellent information, has given me direction in which to take in regards to my 87 Maxima.

- Take Care
- David Steele

 

Be more specific? Do you mean 87 with 93 to get 89 (no problem, however the number is just an est.), or Mobile with Exxon or Wal-Mart gas??? If the latter is your question, makes no difference, every time I have traveled up and down the east coast or out west, good luck on finding the same two brands... Bottom line, refer to your cars owners manual on the recommended octane and use it.

If knocking or pinging start becoming a problem, you may want to bump up the octane rating, if problems persist and your using the highest octane rating, you have more than a type of gas problem...

 

It would be nice if this was a sticky as the topic and this article seem to always spring up. Our vehicles recommend using 91+ octane fuel. When 91+ octane fuel isn't available 87 octane may be used. 87 can be used because our knock sensors will kick in. Our timing will be retarded and gas mileage can slip as much as 10% not to mention a loss in hp. Along with the this, deposits can also become a problem, however it's usually the other way around, ie: if you have a car that recommends 87 and you use the slower burning 91+, it'll cause deposits. I'm going to stick with what Nissan "Recommends" since they built the engine around this octane rating. I run 87 in my Titan because that is what Nissan recommends for that vehicle. $1 or $2 extra each fillup doesn't concern me. I fill up 2 times a week so let's say It'll cost me anywhere from $100-$200 a year. At $200 a year, that's roughly 50 cents a day. Less than half the cost of a bottle of Pepsi.

 

Can I just ask a stupid question since I'm a noob?? Why on the inside of our gas flap, does it say "For Maximum performance it is suggested to use premium gasoline?"

 

Because 91+ is required for optimal performance.

 

No you can't ask an idiotic question that is answered in THIS thread!! Scroll back up and read the thread again.

 

Well that is why I'm asking. B/C I did read all the posts.

Owning a VW for last several years, it says to run 87. But on a turbo'd VW there getting more power/efficiency out of 91+.

So I was clueless with the amount of HP the Maxima puts out, why you have the above article stating that higher octane doesn't matter, when it's proven too??

 

You misunderstood the article and still missed some key points made in the thread. The article basically says that running higher octane that the manufacturer recommends is a waste. Putting 91 in your old VW would have been a waste. Putting 100 octane in a maxima is a waste unless you're doing something like nitrous or turbo.

 

noob>knowledge

 

Putting at least 91 octane in our Maximas however will provide you with the best mileage and power. Going higher than 91 won't provide any appreciable performance in Maximas.

 

It is funny how all these people in the 4th Gen forum say how incredible their Maximas run and what an increase in mileage they see when burning 93 octane!!! Oh, and how much their cars love the 93 Octane! Or the other favorite, "my knock sensor went bad because I used less than premium gas"!

 

As opposed to what? 87 octane? Both the 4th and 5th gens will run better with premium. In fact, the 3.0L is more sensitive to lower octane than the 3.5L because the 3.5 heads have better cooling. It's dyno proven that premium is a lot better, not only for power, but smoothness. Go look at the dynos and you'll see that premium is good for 15-20whp/tq at all RPMs and that the regular fuel's hp/tq curves are a lot more jaggy.

In some places, 93 is not available and unnecessary, like Utah. At higher elevations, 91 = 93 is at sea level. In utah, regular is 85 octane and midgrade is 87.

 

If you READ the whole thread we were comparing 91 to 93 octane.

 

Sorry, maybe people read faster than their comprehension level, the bolded quote stated: “Using a higher octane gasoline other than your owner’s manual recommends offers absolutely no benefit”. Maximas ARE high performance engines, thus almost all Gens of Maximas need the 91-93 Octane level in order to perform at peak proficency. If however you owners manual states 89 octane, using 93 would be a waste...

 

Um, no, if you READ the whole thread, it speaks about regular vs. premium. Not, 91 vs 93. In places where 93 is available, 91 usually isn't available at all. Premium fuel should be used in your maxima whether that means 91 or 93 in your area.

reg mid prem
Most places 87 89 93
Some places 87 89 91
High elevations 85 87 91

nissan owners manual says "improved vehicle peformance NISSAN recommends the use of unleaded premium gasoline with an octane rating of at least 91 AKI number (Research Octane number 96)."

It says "at least 91." 93 is not available in many places in the country, but should be used if available. 93 is not an exotic racing fuel, but a common fuel found in most of the country. You should not avoid using 93 when available or try and find 91 instead of 93.

 

Yes, agreed. I was just kinda agreeing/emphasizing with the point where going above 91 is a waste of money. I use 93. I can't get 91 here. My owners manual says 87 is OK too. And it says 85 is OK in the mountain states of USA. I have used 87 89 and 93 all seem to run OK, but I use 93-99% of the time. Maxima's are engineered to run best on 91+, but are also engineered to accept the other availible octane fuels. I have never heard pinging from my engine, but you can't always hear it right? Also the knock sensor thing, every week someone writes in that they used 87 oct. and blew their KS...ridiculous.

 

Here in Central Cali it's 87, 89, 91. We used to have 92 but now it only goes up to 91, I don't know why they lowered it. I was told when I bought my car in '94 to use premium , preferrably Texaco or Chevron.

 

This is kinda common sense if you just google and tad bit. But the debate never ends hehe.. Good info btw.

None the less, use the RECOMMENDED octane in your OWNER'S MANUAL. PERIOD

If it needs 91, anything above it or at it is good enough. Please don't make your car run into situations you don't want it to. You can put 89 or 87, and the reason for that is because in extreme situations where, your short a penny, or whatever and need gas, you put whatever you can get. Luckily our ecus and knock sensors come into play. That's the only valid reason why anyone should put the below octane rating of their cars.

BTW, some ping or knock could be heard on older cars. They are more noticeable and after a tuneup and everything, if the car still pings, go up a grade.

 

This is all true. I too have used all of the above octanes plus 85 octane here at 6K feet elevation (but not below 2K feet elevation -- Nissan says 4K feet). Because I'm not racing my Max, I could not tell any difference in performance using all of them. And my mileage seems to be more dependent on other operating conditions (cross or head winds on the highway and outside temps -- get better mileage in the cold) than on the gasoline's octane.

I also have to agree that in a Max you will get better dino HP and torque performance burning premium. But, like racing, here you are pushing the engine for maximum performance. I don't do that in my driving and so only rarely do I burn premium in my Max.

If you have a turbocharger on your vehicle, you should get the highest octane gasoline you can buy. And you may find that 93 octane is not high enough.

The article heading this thread is basic, good information about premium vs regular gasoline. If you want much more detail on "Octane and What It Means" (possibly more than you wanted to know), see my earlier thread with this title in the fluids section of this site:

http://forums.maxima.org/showthread....6&page=1&pp=30

 

so what do you guys think is optimal for a 3rd gen vg?

 

With a VQ engine of any generation you will always get optimum (maximum) performance with premium gasoline. It will give you the best acceleration and will minimize any tendency for engine knock. As for optimum performance in miles per dollar spent on gasoline, the question remains open and probably varies from engine to engine. IMO the only reason to pay more for 93 octane over 91 octane (that Nissan recommends) is to further reduce the possibility of engine knock.

I personally feel that I get the optimum mileage per dollar in my Max by burning regular. For you to make that determination, you need to try 89 octane mid-grade and see what performance you get with it in your Max. If you get more than occasional engine knock, go back to premium and stay there. If you don't get any engine knock, then try 87 octane regular -- and go back to 89 octane if you get more than occasional engine knock. If you only get very occasional engine knock with regular, it shold work fine in your Max.

Others have said that they can tell a difference in mpg between different octane grades. I can't. But you should check to be certain that a lower octane gasoline is not noticably reducing you mpgs. If it's not, then that grade should work for you.

If you ever decide to do any racing, you should be certain that your tank has at least 80% premium in it.

 

I'm wondering why Nissan recommends against additives such as injector cleaners. Every so often, not a lot, I run a bottle through just to make sure the 'jectors stay clear. I don't think this would be detrimental to the car. What do you fellas think?

 

^^^
Irrelevent to the subject of the post. I imagine that Nissan recommends against it because there are a lot of snake oil additives and cleaners. I would say that BG or Chevron cleaners are the only ones you can trust.

 

I run a bottle of Techron through the tank about 500 miles before I do each oil change. Using Mobil 1, I only change the oil every 7,500 miles (maximum Nissan approved change interval). This seems to be adaquate for keeping the injectors and the engine clean.

 

Most of the Octane ratings are established by the State, what is considered 91 in Cali can be considered 93 in Colorado, as long as your owner’s manual says to use premium, that’s what you should use, as for brand, since almost ALL US gas comes from the same refineries regardless of brand, you can bet that Wal-Mart Premium and Chevron Premium are pretty much the same. I have never seen an owners manual specify which brand, with that said, don’t get pulled into the best brand gas because all your doing is paying more for a gas that has an equivalent at a cheaper price.

Check out the Oils & Lubricant section on the Org. There are lots of threads about gas that put the myth to bed…

 

Ever heard of LubeControl FP or Gumout Regane?

 

Your first statement above is completely wrong. The states do not have much to say about octane. Most have quite a bit to say about other gasoline specs like RVP and gasoline composition. Thus you get the California botique gasolines that cost so much because so few refineries can even make the stuff. It is now reported that there are more than 40 different gasoline grades across the US. I'm not talking about regular, mid-grade and premium. These grades are Federal and State mandated gasoline compositions for different states and in some cases for different parts of a single state like California. Just recently Denver mandated "special" gasoline and because of the distribution system we end up with it in Colorado Springs too -- at a higher price than before.

You are correct about the Fluids and Lubes section on the Org. I have a few threads and many posts there.

 

Thanks for the correction and detail, my comment was just a quick example oh gasly one... Anyway since you stated yourself that they are both federal and state regulated, how is my comment completely wrong...

 

The composition of gasoline is regulated by the states, but you original statement was that Ocane was regulated by the states. There is a differece. There are some states that mandate minimum octane, but certainly not what octane must be in which grades of gasoline.

 

Like I said before, my statement was generic in terms. Lets try this and leave it at that:

The octane rating of gasoline marked "premium" or "regular" is not consistent across the country. One state may require a minimum octane rating of 92 for all premium gasoline, while another may allow 90 octane to be called premium. To make sure you know what you're buying, check the octane rating on the yellow sticker (which federal law requires to be displayed) on the gas pump instead of relying on the name "premium" or "regular."

Enough said...

 

Maxima owners should be using premium gas, whether it is 91 or 93 octane in your state. I don't think that most states regulate what is called "regular" or premium. I think it is more market driven. Like you said, the feds require that the octane number be labeled and the states usually enforce it.

In Utah, 93 would be overkill for most cars that need "premium" gas because of the elevation. Because of the elevation and low humidity, 91 octane here = 93 octane at sea level.

In Idaho, the lower elevations have 93 octane and the higher elevations have 91 octane for premium.

 

Actually I think both of you are generally correct.

After a number of stations in some states were caught selling lower octane gasoline for premium, a number of states have laws that specify the minimum octane that a station in that state can label as premium. Some even have that minimum for mid-grade and regular. So while they don't specify exactly what octane each grade must be, they do have a minimum octane for a grade. This does not apply to all states or all grades of gasoline.

The Federal octane label is a good start (unless the station is cheating). The minimum laws in a state allow the state to go after that station -- the Feds don't enforce the labeling law that requires the posting.

Finally, low humidity has nothing to do with a car's octane requirement. But elevation certainly does. Here at 6 K feet above sea level 85 octane regular is (for most vehicles without a turbocharger) like burning 91 octane a sea level due to the effect of altitude on most vehicle's octane requirement. The effect is about 1 octane reduction for each 1 K feet of increased elevation.