Higher octane=better gas mileage?
 

Hey guys I read somewhere that using higher octane might give me better gas mileage. I use 87 right now because of price but if higher octane might give me some more miles it would save money in the end. Any info anywhere? Thanks for the help!

yeah it does...higher octane = ecu can advance the timing more = better gas mileage...

Not so fast. I have read differently. Also, Silvermax has data on this, he will post here soon. :reading:

I ran a test for 3 months using 3 different 91 octane branded gas, purchased a 3 different stations and I never got better mileage than the 89 I was running. So if anyone says you'll get better mileage, run a test and see for yourself. I gas up 1 per week, pretty consitant on my weekly mileage, so 4 tanks per station was a pretty long test. btw, I get ~24 mpg.

here we go....

just read a few of the many threads already covering this topic.

Yes, yet another person has proved it. So many people think higher octane number=higher gas mileage.

Recommended octane of gas aids and retards the knocking you will get if you use lower octane. ECU will perform better as well as the care when you put the recommended grade/octane of fuel. Performance is the key not necessarily better mileage.

In theory, using higher octane fuel in an engine like the VQ will result in higher mileage. The advancing of ignition timing does result in more efficient combustion of the charge in the cylinder. On the other hand, whether anyone will see or realize the difference under actual driving conditions is highly debatable. The driver would have to constantly discipline himself (or herself) to throttle back a tad to take advantage of the efficiency gain. Perhaps if one did an almost pure highway run, over the same stretch of road, and used cruise control set to precisely the same speed, but how realistic is that? For the vast majority of users, they are simply going to step on it and go, totally obscuring the advantage.

It is also important to note that many engines are not set up so that their ECU can advance timing to take advantage of premium fuel. Whereas my G35 does, the V-8 in my wife's Sequoia does not. In that engine, premium is always a total waste of money, as it will produce neither performance nor efficiency gains. So IMO, the initial question to answer is whether or not your engine is one of those that can make better use of premium gas in the first place.

Coincidentally, yesterday, I drove from Pensacola FL to San Antonio TX, about 725 miles. The first tank of gas was about 3/4 87 octane, the rest 93; and the second tank, 18 gal of 20 was 93 octane. Under essentially the same cruising conditions, the first tank (lower octane) got me 23.5 mpg; the second tank (higher octane) registered 24.5. Of course, this is just two tanks, and pretty close numbers, so it could well be something else, but who knows...

Anyone who wants to find out the right answer, read this:

http://forums.maxima.org/showthread.php?t=450870

If you're saying that the "right answer" is that it's virtually impossible for an individual to generate meaningful, conclusive data through real-world use of a single vehicle, then I agree. That thread shows just how difficult it is to do this. The original poster himself notes several times that his results are inconclusive and may be the result of factors other than fuel grade used.

Beyond this, what I find striking amongst the fuel threads here is a complete absence of anyone managing to explain away the effects of ignition timing and how the ECU and knock sensors in the VQ adjust timing based, in part, upon the octane of the fuel being used, and why this timing effect will not produce more efficient combustion.

Too much of anything isn't good for your car.

Absolutely brilliant! I wish I had thought of that.:yeahright :tardsmash :fart: :jeffy: :stupid:

Incredible insight!! :ughbow:

Here's my question to you. Even if 93 octane gives you better mileage, is it going to offset the extra price you're paying at the pump for the added octane? :surprised

Its only like .20 diff per gallon so its not really a big deal.

.20 x 16 gallons = $3.20

some people who fill up 4x a month....that will be $12.80 saved per month...woohoo, thats a dinner and a drink at Dennys...

Yeah thats true. Im still a student so I dont really have any expenses except insurance/gas (cell phones free) so I dont mind spending the extra money on premium.

well after all posted above I just want to say that
1. our VQ's seem to be more sensetive to different octane # For example whe i tried 89 ones in my max tranny was constantly shifting ti lower gear -> higher rpm, which's weird in city driving.
2. That thing a/t toyota does makes sense their engines won't make difference whether you'll pour 87 or 93.

91 Is the least i'll ever pour in my baby :)

I agree with your first and last, but not so fast as to "2.".

Click here: http://www.toyota.com/images/vehicle...amry/specs.pdf This is the Toyota 2GR-FE 3.5L V-6 as it appears in the present (2007) Camry. As you can see, on the specified regular 87 octane fuel, you get 268 hp.

Now click here: http://www.lexus.com/models/es/350_specifications.html . This is the very same 2GR-FE 3.5L V-6 as it appears in the Camry's big brother, the 2007 Lexus ES-350. Lexus goes ahead and "requires" the use of premium fuel and presto, the hp is up to 272. A small margin in this engine, but a margin nevertheless.

Note especially the language in Footnote (2) on the linked Lexus page regarding the use, or non-use of premium gas in this engine: "[2] Ratings achieved using the required premium unleaded gasoline with an octane rating of 91 or higher. If premium fuel is not used, performance will decrease" (emphasis added). From Toyota/Lexus itself...