GatorGreg

If my GX required 91 I 'd use it. But it doesn't so I usually don't. Since my GX only requires 87 I have complete peace of mind using 87 so long as it's from a decent station. I'm pretty sure most of us can easily afford the extra 250 after tax dollars per year, but I'd rather use that money for pizza and beer, er, I mean charity and retirement

K-Bud

the first good resonse i have heard for saving the extra $300 or so dollars. putting it towards beer


haaaaaaaaaaaaaaaa

ZIP

The '04 GX had a 9.6:1 compression ratio and no VVT-i and required 87 or better octane fuel.
In '05, VVT-i was added along with a bump up in compresion ratio to 10:1 and an octane requirement of 91 or better.
The Lexus New Car Features manual shows no significant changes in powertrain or the Engine management between '05-'07 GXs. Maybe the sticker was added coz people were still pumping in 87

BobsGX

The engine in the 4Runner is rated at less horsepower and torque than the GX. Even though it's only a 3 hp and 17 ft. lb. of torque difference, that could be why it can use 87 octane fuel. I also noticed that the GX gets 1 more MPG highway than the 4Runner. Also where is it in print that the 4Runner can use 87 octane fuel? Thanks

ZIP

07 4Runner New Car Features manual states 87 octane or better.

Power difference may be due to more agressive mapping in the ECU such as timing tables, which may in turn necessitate the higher octane.

The G Man

The 05 and 06 GX as well as all 4runner do not require 91 octane, the manual states 87 octane min. 91 octane recommended. They both have 10:1 compression ratio as well as the 07 and 08 GX.
Going back to the towing with 91 octane discussion earlier, it would make sense that putting in 91 octane will increase 17 ft-lb torque and would be a good idea if you are towing. The 3 horse power increase will not be notice in everyday driving. If it is the aggressive mapping of the ECU that increases the torque, then it can also retard the timing when using 87 octane with no harm to the engine. Seem to me 91 is a good idea when you are towing, but to put 91 octane in just to gain 3 horsepower in everyday driving does not make sense.

ZIP

Which "manual are you referring to? I looked up the specs in the Appendix of NCF manual provided to the dealers by Lexus/Toyota and it most definitely stated 91 octane in the fuel requirements.

The computer can only compensate so much. Under load such as uphill driving or heavy acceleration you may experience pinging or preignition if using lower than the recommended octane. Driving habits and conditions are also key. If you're happy with the power you have using the cheaper fuel thats great. I use 87 in my 07 GX too... but I'm not planning on keeping it very long... I'm selling it next week

The G Man

I am referring to the 05 GX manual. You said that you are using 87, have you ever experience any pinging? I have been using both 87 and 93 octane, The only time I have notice a slight difference in accelaration is during towing otherwise, no difference in power or MPG.

ADVocate

As someone pointed out about the years prior to 2007 (I have a 2004), there is no statement requesting anything higher than 87 in the manufacturer literature. They may have amended that in later years (as in your example of 2006), but that does not hold validity for the previous years.

I have a good understanding about the formulation of higher octane fuels and the Organic chemistry associated with it. It is not the octane that causes problems within the engine, it is either impurities or lack of some detergents. The detergents are included in all brand "A" fuels, in different concentrations depending on grade. The Octane rating correlates to the speed of the fuel burn.

And as far as being a country of excess, your right, we suck. I like the ride, but I don't have to enjoy (nor am I proud of the fact) that the vehicle is a pig where fuel consumption is concerned. I didn't buy the vehicle because it uses more fuel, that would be asinine of me. Actually, I despise the fact it uses as much fuel as it does. Not just for the sake of expenditure, but do I feel a bit like a toad because it is rather environmentally unconscionable. I am not necessarily a tree hugger, but I do think at some point we will have to atone for bad behaviour.

just my 2 cents ... other opinions may vary

GGGXXX

Sign next to the fuel cap highlights premium and manual states 91 octane recommended - -wasn't there a bump of from 235hp in 2005 to 263hp in 2006+ model year. I have the 2006 and the hp is 263hp so maybe Lexus wants us to use Premium given the changed engine hp (even though 4.7L)

The G Man

The 2005 GX has the VVT-i engine as well and there is no premium statement on the fuel cap. The above statement may be true, Lexus want to differentiate the GX with the 4runner V8. In order to do that, they need to add horse power and torque. There were some post in the 4runner forum of people who had the 4runner V8 on a dyno with regular and premium fuel and notice a slight increase in horsepower and torque with premium.

BobsGX

It took Lexus until the 06 model year till they realized they forgot to update the decal on the fuel door. I for one have tried both 87 and 93 octane fuel in my GX and I notice that the GX on premium fuel does respond quicker in passing situations and gets slightly better mpg. Now whether that warrants the extra 20-30 centa more a gallon, that's your decision.

The G Man

I agree, I think all 05 and up GX and 4runners have the same engine and same ECU programming. The extra HP for the GX and being able to use regular octane gas on the 4runner is more a marketing thing for Toyota and Lexus. Both engine can run fine on 87 but they also can gain 2 or 3 horespower with premium gas. Most drivers will not notice a 2 to 3 horsepower gain in a 270 horsepower engine, but if you are towing, you will notice that 17 ft lb of torque. Gas mileage wise, I have not notice any differnce. I been going back and forth with 87 and 93 octane and try to calculate gas mileage manually for 2 years. Sometimes I get better gas mileage with regular and sometimes with 93. Over all average: 93 octane was 0.3 MPG better, but thats not a meanful number in my opinion.

KVA

I run 87 and my GX states it "Tastes Great, Less Filling!"

BLKGX470

I've tried both 87 and 91 to see if there was a better mileage difference but it didn't seem to matter.

I've always ran 87 ever since. no knocking...running smooth!