From the previous post: I suggested using the lowest price fuel instead of premium, originally for a faulty reason, which was quickly corrected. Many came to say that higher octane fuel will give better performance and improved gas mileage. I doubted both of these claims, but agreed to perform my own personal test. These results really cannot be scientific, as the experiment was not nearly controlled to that level, but it reflects my own personal experiences.

3-18-06 - 3-31-06: Low grade fuel
126071 - 126899 miles
828 miles/31.929 gal. = 25.933 mpg

3-31-06 - 4-15-06: Premium fuel (93 octane)
126899 - 127593 miles
694 miles/28.309 gal. = 24.515 mpg

For the period of time 3-31-06 - 4-15-06:
Average price of low grade $2.684
Average price of premium $2.874

Premium fuel averaged $0.19 or 6.8% more than low grade fuel and delivered 5.6% lower fuel economy. The cost to me to drive from 3-31-06 - 4-15-06 was $80.50. Had I used low grade fuel and gotten the same gas mileage I received when using low grade fuel, it would have cost me $71.83. I feel this experiment cost me $8.67 in half a month.

There were no substantial changes to driving habits, routes, roadways, etc. Both periods of time consisted mostly of me driving to work with one long highway trip to the same destination. There was no noticable change to vehicle performance.

I have no explanation for why mileage went down with premium fuel, but this supports my continued use of the lowest cost fuel available.

 

Good research, but since you're driving mostly highway, that sounds right. Rule of thumb= better mpg with premuim for city, better mpg with 87 for highway. Contact SilverMax04, he has done similiar research.

 

Here, found it, do some reading

 

This thread sucks Part II

 

Now THAT was insightful!

 

If you read the first thread you would see nothing but the truth.

 

wow i knew high octane gas wasnt that much of a importance. thnx for saving me mullah

 

how about mid grade???

 

I say use whatever you want or can afford. In the last 7 years I've used gas from the US and no less than 5 other countries of varied prices and octanes. These cars can handle them all, hell I even use corn fuel every once in a while. So if you think 91+ octane is the way to go, go that way I'm sticking with 87.

 

By looking at the comparisons

If you put 28.309 gallons of each octane you would have gotten roughly 734 miles using 87 octane and 694 miles using 93 octane. and 734-694 is roughly 40 mile gain on 87 octane.

So roughly you gain 40 miles on 87 octane which is gonna be $5.74 cheaper.

But for me I still belive 93 octane is better because I got roughly 30 mpg on a 400 mile trip using 93 octane. So it your choice.

 

You should do the experiment with 2 or 3 different known "brand names" of gas. Joe's Fish, Chips and Petrol may not cut it if that is what you used. Using 87 octane then filling the next tank with 91+ may not give the ecu enough time to adjust the timing, it may take a couple tanks of 91+, etc. especially if all you have been running was 87 except for the experiment. Tire pressure must be the same for both tests (not sure if you checked this) tune up up to date etc.
You would only have to count the work week if the distance is the same because weekend driving is barely ever the same. The study was only mpg, try time/acceleartion trials and realize the max moves like a constipated slug with 87 octane.

 

Now I will use 87 FO LYFE PLAYA. Thanks man, you have opened a new world of gas to me.

 

its also a known fact that using a lower grade gas can contribute to ruining valves etc with elevation changes, here in Ut that happens to be quite a bit so using a higher grade fuel to help prevent that might be more useful in certain areas.

not to mention i can't (shouldn't) spray my 125 shot using anything but the highest grade possible. there are reasons as to why higher grade gas is better to use, not just nitrous applications but for the overall performance of the motor...

for 5 or 8 dollars you saved, are you really on that tight of a budget that it would make a difference?

 

Using 87 on a car intended for 93 is NOT helping your motor or fuel system. I would always use the intended fuel that Nissan suggests in any car. They do testing for a reason....you really don't think Nissan tested many different octanes on their engines. That is how they come up with suggested octane rating.

 

that thread

 

It makes sense that the lower octane gasoline would provide better MPG on the highway and lower MPG in the city. Lower octane gasoline combusts more readily than high octane gasoline. This might be of some benefit in low-load cruising situations while in city driving, the higher load increases the occurance of pinging with the lower octane fuel and the ECU pulls timing, reducing MPG.


BTW, i will always use higher octane fuel in my vehicle, but NOT because the lower octane rated fuels will make my VQ blow up like some simpletons here like to think.

 

Just because your VQ never blew up because of lower octain doesnt mean others havent.

 

Idk i get an average of 400 mpg using 93. My trip is never the same and it's always a various mix of highway and city and i get the same exact thing. Last week i recieved 407mpg the week before it came to 397. I feel better that my car is using 93 and i can't really complain about mpg. My 2005 altima 2.5 didn't get even close to this and it was a 4cylinder....

 

pocket change

 

Link?

............

 

Joke?

............


Damn south florida folk.

 

Nothing i read in the 4th generation forum surprises me anymore so i assume people are serious no matter how rediculous it sounds.

 

I thought if your car was on one type of fuel....such as 87 octane...that it takes 2 tank fulls of burning a newer gas...93 octane...before the 87 is completely removed from the system. In any case when I open my gas tank door it says "premium fuel recommened for optimal performance" so I just go with the flow...premium FTW!

 

Use the higher grade octane fuel. In the long run it will save you. Used 87 when I got my Max, 2 months later found out that my spark plugs were fouled and my fuel injectors were clogged from it, not to mention the massive amount of knock in the engine when accelerating somewhat hard. Use 91-93 now and get a little better gas mileage, no knock and flawless performance. Car and Driver did a test a while back on the effects of premium vs regular gas. For cars that don't recommend premium, there is no change but for premium recommended cars, when using regular gas the power in the engine went down about 12% in all catagories including gas mileage. So think about that next time you are at the pump, find a gas station somewhat on your way home from work that has the 10 cent price difference for premium instead of the standard 20 cent.

Also, junk such as bleach and other additives are more abundant in the regular versus premium. Chem 451 lab is great for this.

 

Exactly, saving a few bucks isn't worth the potential damage IMO.

 

What potential damage? And based on which of your personal experiences?

 

One thing that you need to consider is that it is highly unlikely that there is any statistical diference in the numbers you have provided on MPG.

Depending on what you had in the car, the terrain you were driving on, and the amounts of various types of driving you were doing it, and etc these things all will cause error in this type of a comparison. Even "similar" driving trends can cause that much error over these periods of time.

In the end, what really matters is the chemical energy available per gallon of fuel, which is not different enough between 87/93 octane to be meaningful. However, if your premium fuel was 10% ethanol and the regular wasn't then you can reasonably expect the premium to get ~3% less mileage.

If you want to be cheap and use regular 87 octane then just do it. I have used 93 octane for about 100k miles and 87 octane for the last 60k miles. It will not hurt your engine. Performance will likely take a small hit from some timing being pulled.

 

man seriously please cut the crap... the sticker says 93 recomended thats all the info i need

 

Stop making these stupid threads. In before close

 

thats weird, b/c for the first 15k mi i had my car, i put in 87. and for the next 15k mi i put in 93. w/ the 93, my gas mileage went up 40miles/tank. i did the math like this
----one gallon of 87costs $2.68.
----one gallon of 93 costs $2.88.
at $.20 more per gallon for 93@14 gallons, i spend $2.80 more per fillup. but i get 40miles less per tank. at 2.68$@25miles per gallon, for me to get those miles back, i would have to buy 1.6 gallons ($4.28) in 87octane. so by filling up premium, i am SAVING $1.49 per fillup.
if u wanna be cheap get the premium. if u wanna get ur moneys worth, get the premium.

 

Wait till it's summer vacation and I get you some real numbers using good gas. I am not saying you are wrong yet, but I will have sticky material to end these type of threads.

 

^^^ Put it to an end! STICKYYYYY

 

OCTANE is a measure of the fuel's tendency to combust SOLELY due to heat via pressure increase, WITHOUT any external spark source.

So that what this means is that any decent spark plug can light off 93 octane just as easily as 87 octane, all else being equal. Combustibility from a spark source doesn't change between regular and premium. The energy content between premium and regular is also about the same.

 

++

The energy content per unit volume is the real story here.