CVsIS250

Damn, I don't think that I have EVER seen anything above 18.2 from my computer with or without 93 or 87.
CV

sayadil

I have noticed slightly better averages from ESSO (EXON) n SUNOCO gas here in Canada. i averaged same with 87 or 91 gas so i stick with 87. Car is little more responsive with 91 but not worth the price diff of about 10 cents a littre here.

I6turbo

iTrader: (1)

The driving conditions were pretty much identical EXCEPT for the average MPH as posted. Lower average MPH meant that I spent more time driving in low speed limit zones and less at 65 MPH on the highway. I spent very little time in stop and go taffic, but a good bit in 30-45 MPH zones. By and large, all of the driving was grand-ma style -- easy on the throttle.

The tank that averaged 32 MPH included about twice as much 65 MPH highway driving as the other tanks.

My testing so far is too small of a sampling to really be meaningful, nevertheless if you throw out the 32 MPH tank (because the average MPH was more favorable to good mileage than the other tanks), 93 octane costs $.01 more per mile driven (18 cents vs. 17 cents per mile). If you include the 32 MPH tank, then 93 octane costs $.006 more per mile based upon $3.00 for 93 octane and $2.80 for 87. Who knows if there are any other benefits to using 93 octane, or if I'd have seen a different result if I drove harder (some full throttle acceleration, etc.)?

I'm continuing to keep track of mileage, but I've returned to driving the LS430 on weekends and longer trips, so I'm racking up miles on the GX at a slower pace now.

I6turbo

iTrader: (1)

I told you in the other thread that the Ash Blue with charcoal interior gets the best mileage (plus all those other advantages).

hsk73

How are you guys getting 17-18mpg!!??
Only filled it up twice so far... But, haven't seen anything above 15mpg....

CVsIS250

DAMN! You were right!

CV

GXRick

My 06 GX is now 6 months old and has about 11,500 miles most of that using 93 octane fuel.After reading the online debates about 87 vs 93 octane, I decided to keep very accurat records using both fuels. My biggest concern is the loss of power from using lower octane fuel. My goal is to determine whether I get the same acceleration using 87 vs 93 octane and to determine the cost per mile of each.

Since early August I've been using 87 octane only.

I've burned 5 tanks of fuel running around Atlanta, mostly on secondary roads but a little time on interstates. Here in metro Atlanta, interstate driving means a very slow commute (not me, I work from the house) or flooring the gas, hit the brakes, floor it , brake, floor it, brake. I'm not an aggressive driver, but I do drive fast.

I burned 4 tanks of gas on a trip to the beach and back, again using 87 octane. Once at the beach I only made 1 trip to the store.

Using only Chevron gas except for 2 tanks of Shell on the beach trip I got an average of 13.3 - 13.62 around town. On the road I averaged 16.97 miles per gallon. I guess Nautical Blue cuts down on the mileage.

I also did 8 flat out acceleration runs to 60 mph, in both directions during mid-day on dry, flat roads. My wife's an engineer so I used one of her accurate stop watches from her time study days.

The fastest time was 8.4 seconds, the slowest was 9.6, the average was 9.2 seconds, 0 - 60

My plan is to begin using 93 octane when I fill up this evening. After 3 tanks of premium, I will begin keeping records of mileage. When that is determined, I'll do some acceleration times.

It will probably be about 6 - 8 weeks before I post the results.

Rick in Atlanta

hsk73

So it's okay to use 87 octane?? No harm to the engine??

The G Man

On the 06, the gas cap saids 91 octance require, on the 05, the manual saids 91 octane recommanded. They both have the same engine, dont know why Lexus change the premium fuel requirement. 03 and 04, the engine is different, the compression ratio is lower, so you can difinitely use 87 octane.

I also have try both 87 and 93 for a few tank at a time. The 93 does make a difference performance wise. Barely noticable during everyday driving and at low rpm, but difinitely noticable at higher rpms. Gas mileage wise, on the computer, it show about a 0.5 mpg difference.

sayadil

as far my knowlege you can use definately use 87 with GX's with the older engine type.. (4.8 ltr 225 horsepower one)
the newer engine should use 91 or higher.

According to my tests on 04 gx. i notice same milage in my daily mixed driving. however putting higher octane makes the engine slightly more responsive... but not worth spending the extra dough in times when gas is already so expensive and if doesn't improove milage then why bother. better acceleration (though hardly noticeable) doesn't really help in cities like toronto with so much traffic.. there's hardly room to accelerate...

hsk73

So... since I have 06... I should stick with premium gas... huh?

How about using 89!!

familyGX47

Did any one see better performance with premium gas (Octane # 91) compares with regular #89?
Mike

GrdnRxR

This came up on the board here about 2 years ago... I tried both and didn't see a difference in MPG but lost just a little power.

SirSkrip

I always use 91, and i actually did try the low 87 once, and I did notice the difference in power.

Skip

Never noticed any difference in mileage or power with 87 or 91. It does not say anywhere on the car to use 91. My IS 350 and my wife's GS430 both say premium fuel only on the filler door.