pump142

my 06 gx says to use premuim 91 only

Chris98vob

I have both a 07GX and 06GS and everything I have read on both engines indicates both a mileage and performance hit with less than premium fuel. The variable valve timing computer will retard timing to avoid detonation which will almost always cause both of these issues. Basic calculations I did at the time I researched it shows the additional cost of the premium fuel was cheaper than the loss of the fuel economy.

Chris

nate579

iTrader: (4)

Lexus kinda contradicts itself. Labels around on the vehicles says "premium fuel only". And the owners manual "recommends" 91+ octane. In any case, 87 octane will cause the engine to retard timing and a small lost of power will results. Other than that, low octane fuel will not harm the engine.

SilverLady

Keep in mind that those with earlier year GXs were not told to use Premium (although it may have been suggested), whereas by 06 it was specified (with the option to go lower if you had to). That's why we seem to get different info from different posters.

I wind up putting in 93, as that is the most common Premium around here and next lowest is 89.

On a percentage basis, Premium is not that much more than the midrange or even regular. 10 cents a gallon meant a lot more at 99 cents a gallon than it does now!

familyGX47

Thanks for the feedback.
We had a 2004 MDX before and we barely notice any difference in power or fuel economy when using Octane 89, except when going uphill. I guess becasue you need the extra power climbing.
It was little confusing to see that the website logged in Regular gas as an advantage over other compatitors, when the manual specified "at least Octane 91"
Yesterday was my second gas fill and I wasn't sure if the regualr Unleaded will work for a $50,000 vehicle.
Mike

dholling13

The manual says 87. If you don't mind the "pinging" noise, or loss in performance then it's your call on an earlier model GX. However, when I tow, I always use Premium or 93 which we have here in MD.

I6turbo

iTrader: (1)

I tested mileage on about 6 tankfuls of 93 and as many on 87 (on my '03 model). There was no stastically valid difference in mileage -- mileage was instead directly related to average MPH. I've never noticed any difference in power at full throttle or otherwise. Things MIGHT be different on a newer model that is rated at a higher specific output.

The way I figure it, my 3 liter Supra can make 600 HP on 93 octane without issue. If the 4.7 liter GX engine can't make 235 HP on 87, it'll just have to suffer.

tyoung88

My 2005 GX470 Manual states:

Fuel selection:
Select Octane Rating 87 (Research Octane Number 91) or
higher. For improved vehicle performance, the use of
premium unleaded gasoline with an Octane Rating of 91
(Research Octane Number 96) or higher is recommended.

I was under the impression that the 4.7L V8 in the GX is the same as the one in the Tundra and 4Runner... neither of which require anything beyond 87 octane gas. With gas prices recently being hiring I switched to 87 and haven't noticed any decreases in power or mileage. Does the ECU in the GX really retard performance when it senses 87?

vxphan

I tried both type 87 and 91. I did not notice any different in MPG as well as performance. But it is noticeable quieter engine when idle and no more knocking.

Thanks

dholling13

I know on my old RX300, there were 3 very sensitive sensors in the exhaust system; all of which went bad and needed to be replaced. Maybe, this is why we need premium gas???

The G Man

If your GX dont ping, you do not need premium. Premium will not paid for itself in increase gas mileage. I also did a test on 6 or so tank full, I got a 0.3 mpg increase on the gas mileage computer, which does not mean anything because a number that small can be cause by other factors.
I did notice the engine running a bit smoother and there was more power climbing hills. During regular driving, there is very little in diff. in accelaration. If you toll, premium is a must. I still have not decided which to use. Since the octane rating for gas is usual a bit higher than it is posted, I been using 89 octane and so far so good.

bobinsofla

Who here is running gasoline other than premium? Curious if anyone with an '07 is running 89 octane and if so any problems/issues.

Thanks,
Bob
2007 GX/White/Tan

Huntington

Running 89 in my '05. No Problems whatsoever so far after 48,000 miles.

The G Man

I have a 05 as well and I run between 87 and 89 octane, dont notice any difference between the 2 or the 93 octane. The 07 GX requires 91 octane right? The 06 and earlier only recommand 91 ocatne and states in the manual that 87 octane is ok to use. I wonder is there any difference between the 2 engines.

Huntington

I live in CA and the recommendation for my '05 is to run 89.