Which grade of gas are we suppose to fill?

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Nov 28, 2003 | 06:02 PM

#41

yanges

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From: San Fernando Valley, CA

Quote:

Originally Posted by snuppy

i'll toss my 2 cents on this subject...

i have an stock auto xB that i run about 50 miles each day, almost all freeway, little to no traffic, averaging 65-80mpg, with a short uphill climb (for those who drive 680 in the bay area, that's the sunol grade)... my first tank was straight from the dealer (unsure of the octane rating)... and averaged 30.9 mpg... (which i was already stoked about coz' i was drving my xterra on the same stretch and got 19 mpg)... i filled up with 76 supreme (91 octane) and got 35.1(!) mpg, which blew me away...

granted, my car is new, and is prolly just getting broken in which might explain some of the improvement, btwn the 1st and 2nd tank... but i never expected to actually exceed the manufacturer specs...

on my 3rd tank now, and it seems on par for the same results... i'll post if u guys want (not much else to think about when driving my box an hour a day, lol!)...

i read some ppl on this board drive 100+ miles per day... any additional insight on the subject?..

hey Snuppy

keep us posted on the 76 gas mileage....

i used 76 when i first got mine and seemed to get the best mileage with it also.....

i am curious to see if you continue to get the high mileage on your xB!!

Dec 2, 2003 | 02:03 AM

#42

bluxb

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From: riverside, ca

basically this is what i've learned about gas and octanes. the reason some cars specify 87 while others specify 91 is the timing that the car is set to. so basically if your car says 87 put 87 because 91 will not really have any advantages. to the people who say they get better gas mileage it could be for many different reasons. your car is breaking in, you drive less aggressively, and just too many factors. but you only need 91 if you advance the timing on your engine to prevent any engine knock (detonation) thats why race cars run 100+ octane fuel (race gas) because the engine is specifically tuned to run with that type of fuel.

Dec 2, 2003 | 04:06 AM

#43

snuppy

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From: Milpitas, CA

alrighty... here's what i've got so far... since my last post i've filled up two more times (for a total of 3 tanks of 91 octane supreme from 76)...

347.6mi/9.902gals= 35.102mpg
346.3mi/9.891gals= 35.012mpg
350.7mi/9.992gals= 35.098mpg

just filled up with 87 octane from the same 76 station... and will do so for the next few tanks to see if there is any significant difference... i highly doubt there will be any significant change, coz' what everyone on this thread is saying makes sense... at least i can say it makes trips to the gas station a bit more "exciting"...

i should add that the weather has been craptacular lately, so that might skew things a lil' bit...

Dec 2, 2003 | 04:14 AM

#44

yanges

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From: San Fernando Valley, CA

Quote:

Originally Posted by snuppy

i should add that the weather has been craptacular lately, so that might skew things a lil' bit...

thanks for the update Snuppy!

that is excellent mileage! are you doing mostly freeway driving as you mentioned earlier? i really have not done much freeway driving and when i do, it is going out Lancaster way and there are numerous long grades so it does not get the highest mileage on those trips...

Dec 2, 2003 | 04:24 AM

#45

snuppy

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From: Milpitas, CA

no problemo yanges...

yah, it's almost completely freeway with virtually no slowdown or traffic to deal with... it's almost relaxing (if only i wasn't on my way to work)... i'll also add that i ride solo to and fro so that prolly helps keep the mpg on the higher end... i use my xterra on weekends (unless there's a meet) so that'll also help keep things consistent...

Dec 9, 2003 | 10:07 PM

#46

doctorcue

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From: Dublin, CA

Ok, well here are my results (unfortunately, I don't have the gas amounts & miles driven as I lost the piece of paper...i know, my bad

)

On 87 Octane: 34.5 mpg
On 91 Octane: 33.7 mpg

For this time frame, I pretty much tried to keep the revs under 4k. This allowed me to easily go the speed limit on the highway in 5th gear. I hit 70 a couple of times, but always tried to keep it 65 mph. I got stuck in traffic twice (damn San Mateo bridge), once on each grade of fuel. So the milage probably could have been better, but at least the delays were equal, both around 45 minutes. So not as nice of a manner as I would have liked to display my findings, but I would say 87 is the obvious choice. For me to loose any milage with an additional expense, no value what so ever.

I'll be interested in seeing Snuppy's results with regular.

Dec 17, 2003 | 05:27 AM

#47

snuppy

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From: Milpitas, CA

just so i don't leave anyone hanging on this... i've been using 87 (from the same 76 station) the last few weeks, unfortunately during the xmas season, i've been carting around more ppl and cargo (xmas gifts) everyday, so really no point in comparing the mpg stats... however, considering i typically had one or two other ppl with me AND varying amounts of cargo AND sh!tty traffic jam parking lot conditions, i'm still averaging about 32.5 mpg... still pretty darn good, all things considered...

Dec 18, 2003 | 06:27 PM

#48

JChan428

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Joined: Dec 2003

Posts: 4

Quote:

Originally Posted by snuppy

i use the trip computer milage divided by how many gallons i put in when i fill up... reset after fill up... :D

do you top off until gas leaks out or what? because those nozzles pops at different times. even if it's the same nozzle. So unless every that posts up there numbers here tops off your tank till it spills, you numbers ARE NOT ACURATE. i'm not calling you guys liars but that's how the nozzles works. so that's why some of you are getting more when switching to 91 or 87. But what actually is happening is just simply because u got more/less gas for the "fill-up" tank.

CORRECT ME IF I'M WRONG.

my 2cents

Dec 18, 2003 | 07:42 PM

#49

snuppy

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From: Milpitas, CA

yah, ur probably right... the pop off times do differ, however, i'm pretty sure that they don't vary so much so that it'll dramatically screw with the results... my #'s are pretty consistent... and even with a variance of 2 mpg either way, i'm still impressed with what my lil box gets... (my other car is an suv that gets 20mpg at BEST)...

i'm assuming most of our mpg tests are done as quickly and painlessly as possible which means as un-scientifically as possible... if anyone wants to top off their tanks, be my guest... i dont' feel like cleaning gas off my quarterpanel & wheel...

happy holidays!..

Dec 30, 2003 | 05:27 AM

#50

daverf230

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Joined: Dec 2003

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From: La Cresenta

hmmmm

Well considering the fact that gas is classified by its resistance to combustion (91 being the least resistant to combust) and the fact that the engine is running at a compression ratio of close to 10.5:1 Id recommend 91 octain if you are the heavy driver thinking that the xb is the fastest thing in the world. If you do not put a load on your car a lot then if u wanna save a few cents, 87. The computer cannot determine if u have 87 or 91 ect. But it will sence all the knocking from the detonation of u put 87 and decide to go full throttle up a mountain.