That is great for you and your 97 Max. The more recent engines actually have a slightly higher compression ratio, but also newer and more sophisticated spark advance controls. Those with newer Maximas should not automatically assume that this will be true for their engines. Suggest you run the same test and make the same calculations to determine if this is also true for them. I know that I can't realistically tell any difference in gasoline mileage when I burned (in the past) premium vs when I burned mid-grade (which is cheaper than regular in Iowa and parts of Nebraska) vs when I burn regular. There were just too many other factors at work -- particularly wind direction (head wind vs tail wind).

 

this thread should be closed :P :P jk..

use recommended octane, and it's all good

 

I'm not sure how much of a consideration it would be in Texas but typically weather in February and March or whenever you took you mpg on the 6 or 7 full tanks would be colder than recently adversely affecting your mpg. Similarly, I'm not sure if they use "winter" gas where you live, but my mpg has gone up by about 10% as a result of the warmer weather and no winter gas which was phased out in early April.

Consequently, I don't have much faith in your calculations. Sorry to rain on your parade.

 

You can try mixing grades. Equal parts of 87 & 93 octane will yield 91 octane -- enough to keep Ol' Monty happy.

 

All of this is valid. Winter gasoline typically is lighter and more volitile (and thus contains less energy) and frequently is blended with more ethanol (also less energy) than summer gasoline. As I pointed out in my first post here, there are so many variables in the calculations you are making that a truly scientific conclusion on what caused a change in mileage is difficult to make.

 

What's the price difference per gallon between 89 and 93...like 10 cents?

When you figure it all out, a tankful of premium is about $2 more than mid-grade. What else can you get for 2 bucks that performs as well?

 

Some of us have tried and noticed no difference in performance. Why pay $2 for no difference in performance?

I do agree that if you have your Max at the track, you would be dumb not to use premium gasoline. I don't do that, and so see no performance difference -- and no reason to drop $2 in my tank for no difference.

 

out of topic, heard that 87 0r 89 gas will clog fuel filter for 95-99 max which cause check engine light will lid, happen to my 98max, any of u? I stick with 93 now for my 98 & 00 max no matter how expensive.

 

93 always for my Max
87 for my Grand Cherokee

 

Plus I suspect you are at altitude and can get by on lower octane gas. I suspect your car runs just fine on 89. Have you tried 87?

 

God I wish there was 93 up here. 91 is the highest up here. I took my baby on a trip back home to TN, and she just loved the 93 octane. Hasn't felt the same since.

 

There has to be a physical reason for a fuel filter to clog. If 87 octane would clog a Max filter, it would clog many other cars' filters. From the standpoint of simple Physics, this makes no sense at all.

 

its $$2.639 for the super 93 here. The funny thing is anytime i use 89 oct i get better gas milage, im guessing its degressing the timing for the pinging. Ive been doing 10 gallons 93 and the rest 87. It runs good and saves a bit, at least im hoping.

 

still using 93 while prices are going up, thinking about going to 89.

 

why not just run 91?

 

$2.79 for 92 octane at getty today. This is just getting ridiculous.

 

he11 no!! super for life come on bush give us a break just raise the price on bananas instead

 

I really see no cost advantage to running midgrade (aka 89 octane), even if it could be used. Mixing equal parts of 93 & 87 will get you there, but in both cases, the savings is 10 cents per gallon (maybe 15 cents in some places).

Let's say you fill your tank every week with 18 gallons of 93 octane. That's an extra $1.80 per week. What else can you buy for $1.80 per week that can do so much? A Sunday newspaper?

Heck...that's like a savings of 3/4 gallon of gas per week, or a 4 percent savings.

IMHO, you can get same savings of 4 percent per week in gas just by slightly changing your driving habits.

 

Anybody heard or seen problems with Wawa gas?

 

I paid $2.89 per on last fill up.

 

93 Is going up again here....Saw it as high as $2.61 at a Mobil
I paid $2.48 a couple days ago at Sunoco, thats where I find the best prices lately. (Even ran into a FREE gas bonanza there a month ago and got $20 of 93! Special thanx to Citizens Bank!!)

Gas Prices are fluxuating so much around here many places have left the cents off their prices up on the signs!! This has been the case for weeks now.

 

you just made my day

 

Ugh

 

What the ? Dam, where was that picture taken?

 

Question for the chemists in the audience:

Are there are differences in specific density among different grades of gas?

 

Who cares? A gallon of gasoline weighs about 80% of that of a gallon of water and floats on top of water. What more do you need to know? If you want to get this technical, join bobistheoilguy.com and you will be well schooled in no time flat.

 

my last tank was of 76 100 octane at 4.99 a gallon.... normal premium is getting closer and closer to that... 3.19 in my area

 

Answer: It depends.

Gasoline is a blend of many different components. Some of the high octane componenants that can be blended into premium are slightly heavier than the lower octane components that are blended into regular -- and a few are slightly lighter. I think it is generally safe to say that from a given refinery regular will never be heavier than premium while premium can be heavier than regular. It is also possible, but not likely, that one company's regular will be slightly heavier than another company's premium.

Hope this helps. (I'm an engineer not a chemist.)

 

What a waste of money. Maximas were designed for maximum performance at 91 octane. If you need higher octane, you either have a turbo-charger on your engine, or you have too many engine deposits and need the engine cleaned up (put in a bottle of Techron as a starter). Otherwise you wasted $1.80 per gallon for fuel that your Max does not need and can't take full advantage of.

Now if the gasoline you bought was 100 Research Octane (R), and not the common pump octane rating in the US which is shown by the formula (R+M)/2, that will have a pump octane of about 95. This is still more octane that the normal Max can effectively use.

 

Don't have 91 in many places around me. It's either 87, 89, or 93. I get the 93.

 

That's OK, but you certainly don't want to pay $1.80 more per gallon for a higher octane than 91. It won't hurt the car to get more octane than your engine requires, only your wallet.

 

i dont use 100 for fun... i have other problems

 

Based on your avatar, it would appear that way!

 

avatar? sig? or graphic in sig? my use of 100 octane does not relate to the bent 19"s 100 octane did not fix my bent 19" wheels

 

Like I said, lol!

 

If you would like your mix to be at least 91 octane (the recommended amount), you would need a 2-to-1 ratio of 93 to 87 octane.

And, yes, the knock sensor is retarding your timing in response to the drop in octane. Personally, I would not want to do that on a long-term basis.

 

See above (re: Mixing 93 octane and 87 octane)...

However, it is cheaper to get 91 octane by mixing equal parts of 89 and 93 octane.

 

First of all, I'd rather have root canals on all my teeth than have anything to do with "Boob, the oil slick, dot com." The guy couldn't find his head with three hands and two flashlights. Anyone who puts gear oil in a blender set on "puree" just to diss Lucas oil additive needs professional help (and not of the automotive variety).

Secondly, I care if only because I can think for myself. Differences in SD, no matter how small, would answer several question I have about using one versus the other.

Yes, I do know that gas floats on water...along with hollow cranial containers.

 

And you are the imbecile who determines fuel economy based on a 158 mile road trip, lol! Did it ever dawn on you that there are a lot of knowledgeable members on that website?

 

There are a lot of knowledgable members on this section (Fluids and Lubes) of this site. I particularly like the postings about lubes -- something I know something about, but can always learn more. But all of you need to determine who are the experts (Bill in the area of lubes for example) and those who are just giving their opinions.

I find in the area of octane, that everybody is an expert. They all know what they know and don't try to tell them any different. In this area (octane) I know more than I do about lubes. And I'm happy to share what I know. Hope this helps those who want to learn more.