darylhuff

If it makes you feel better to spend your hard earned money on more expensive gas, then by all means do that. The fact is that it has been proven over-and-over that if your car does not require premium fuel and it is not pinging, you're wasting your money. Go to http://www.consumerreports.org/ and search for "fuel octane rating". Or read basically the same thing at any number of web sites including:

http://www.straightdope.com/columns/041008.html
http://www.bellaonline.com/articles/art8084.asp
http://theserviceadvisor.com/octane.htm

It's your money, do what you want with it.

gs400jon

Read and heed! My truck runs like a dream on 87 octane.

<VENOM>

Their are many things I could say about Dealers, 1 is it's unreal how much they don't know and how much BS they are full of, now whatever you put in your tank is fine but at least know why, not just cause someone tells you, I've tested the gas at my area stations and the regular is no different then the premium except for the octane.

et415

This is another site that makes me think there are differences among gasolines: http://www.toptiergas.com/

It says:

"TOP TIER Detergent Gasoline is a recently established new standard for gasoline performance. Four of the world's top automakers, BMW, General Motors, Honda, and Toyota recognize that the current EPA minimum detergent requirements do not go far enough to ensure optimal engine performance."

It lists the following brands as Top-Tier compliant:

QuikTrip
Chevron
Conoco
Phillips
76
Shell
Entec Stations

I've always thought that premium gas had more detergents than regular. Maybe the brands on this list also have regular with premium-class detergents...not quite sure....

et415

Well, that's not completely true. I think what you meant to say was "The fact is that it has been proven over-and-over that if your car does not require premium fuel and it is not pinging, you're not hurting your car."

I think it's pretty well established that a car tuned to use premium gas will perform better using premium, even if using regular won't hurt the car. Lexus vehicles HAVE been tuned to take advantage of higher octane (even if they don't REQUIRE premium). I don't think GX470Blue is imagining things when he says he's experiencing power loss.

For me the question is not about whether our Lexuses will perform better using premium (they should), but whether Brand X gas is better than Brand Y gas.

In another post I referred to TopTier Gasoline. I did a little more research, and I found this on the GM site: http://www.gm.com/company/gmability/...nt_092704.html
and GM states pretty clearly that not all gasolines are equal.

I also found this FAQ Chevron Supreme (I don't think it applies to regular) on the Chevron website: http://www.chevron.com/prodserv/fuel...tech_gas.shtml . If the brand of gasoline of gasoline doesn't matter, then it seems like the Big 3 US automakers are pretty stupid having Chevron Supreme shipped from Kentucky all the way to Detroit when they do some of their EPA testing, as it states in this article.

I admit I've been filling up with Costco Premium since I got my GX...but maybe I'll switch to Chevron or one of the Top Tier brands (a local 76 isn't that much more than Costco if I use my 5% off gas card).

loflin

I think in some of the previous replies, people are confusing the term "improved peformance" with the "race car" type performance.

Improved performance does not necessarily mean your 0-60mph time or 1/4 mile top speed and time.

For a unloaded GX on flat roads around sealevel, I doubt you could detect much difference between reg and prem fuel. Because in fact, most of the time, the engine is loafing anyway.

However, I pull a 5000lb boat/trailer up and down hills, some of the time. In this case, I'm using all the engine has. There IS a difference in "performance".

But, of course, it's a personal decision on whether that is worth the cost difference.

bunka

The plain facts are that the GX (like the Toyota Four runner) does not BENEFIT in ANY way from the use of ANY fuel beyond 87 octane. It DOES NOT get better fuel economy or performance when it gets higher grade fuel. Anyone can put premium in there car if they want too but based on the consumer reports (and other forums), there is no reason to put anything other than 87 octane in the GX.

super_cjc

Many people say that BP is better than Shell. It's interesting that BP is not on the Top-Tier compliant list.

Very informative.

et415

Bunka,

Where do you get your "plain facts"? If, for example, you're referring to the Consumer Reports link that Darylhuff earlier posted, it says: "Most vehicles are designed to run just fine on regular-grade (87 octane) fuel." It does not say ALL vehicles, just "most." Lexus engines are not like "most" vehicles'. Lexus engines are designed to run optimally on premium. The GX owners manual states: "For improved performance, the use of premium unleaded gasoline with an Octane Rating of 91 or higher is recommended." You can use regular in your GX (the engine's computer will compensate to prevent knock), but performance won't be as good. Or am I missing an article somewhere that specifically says that the GX's performance is the same whether you use regular or premium?

<VENOM>

Here's a performance increase you will feel, pull the air box out and a headlight, get a 4 inch flex pipe from HomeDepot connect it to where you disconnected the air box, feed it out the headlight you removed and tell me thats not a power increase you can feel homemade ram air, just seal it up nice with duct tape and cover the new intake hole with a screen door mesh, gotta keep the bugs out of the engine you can follow that up by making the GX lighter by pulling all and everything out thats not really needed, everything but the drivers seat

Thats alone will drop the 0-60 from 8 seconds to 6 seconds

bunka

ET - I use to own a performance Benz and then now own one of the new 04 TL's. Seems this topic comes up on every forum. There have been a number of studies on running higher grade fuels in vehicle that have been designed to run on regular fuel. In many cases, the higher octane fuel does not provide anything to the driver. Only in vehicles designed to take advantage of the higher octane can really make use of the premium fuels. This has been debated a number of time on both mbworld.org and tl.acurazine.com. There are groups on both sides but there were studies done by consumer reports that stated that running premium in a vehicle that does not REQUIRE it, will 1) Only cost you more money and 2) May actually decrease your actual fuel economy. Here's one link
http://forums.mbworld.org/forums/sho...9&postcount=23

et415

Bunka,

I read the thread and found no statement or even opinion that PERFORMANCE will not suffer if regular gas is used. Most of the discussion is about whether the engine would be DAMAGED if regular gas is used. Am I missing something?

Just to make clear what I'm saying:

1) Using regular gas in your GX is fine....it won't damage your truck because the engine computer will retard the ignition timing to protect the engine. And if you don't notice performance degradation (or, if if you do, it's not enough to justify your paying 20-cents a gallon more), then keep on using it.

2) Using premium gas in your GX will result in better performance (for those who can use it). This is clearly stated in the owner's manual and is experienced by many GX drivers, including the original poster of this thead and myself. Not everyone will notice the performance difference because they don't challenge the GX's V8's performance limits.

If you drive around only on flat city streets and crowded highways, then you probably won't notice. But if you're driving at 70mph and need a quick burst to 110mph to pass a bunch of cars, then you'll likely notice. If you're driving up a mountain at high altitude and at freeway speeds, then you'll likely notice. If the GX is loaded with 8 people and their cargo on the roof, and you accelerate hard, you'll likely notice. Are you saying there is no performance difference of this kind when using regular vs. premium in a Lexus GX470 (or similar vehicle that has been tuned for optimal performance using premium)? If so, then I'd be interested in seeing a specific source for this information. If it's just your opinion, then I guess we'll just have to agree to disagree.

Anyway, 'nuff said by me.....

Gohawks63

Very well put. If you're not challenging the engine, then you may get along just fine with a lower octane.

Here is another opinion on the matter. THe guys does have a harsh tone, but it basically states to go by what the manual states.

http://www.straightdope.com/columns/041008.html

<VENOM>

came across this thread in freshalloy.com, a 2005 Nissan Frontier owner dynoed his truck with 87 and 93, 93 actually showed a slight power lose

http://www.reverendbiker.com/frontier/dyno2.htm

it's just for comparison, his 4.0 V6 has similiar compression ratio to the GX and the owners manual recommends a minimum of 87-octane fuel but states that 91-octane or higher may be used "for improved performance."

another thing is most all boards have the fuel debates, which octane is better, but the 4Runner owners all pretty much run regular, the new guys run premium but eventually switch to regular and their are a select few who use nothing but premium

bunka

ET - WHile I understand your logic. It may be a little off in this case. The GX is actually TUNED to the regular fuel octane and CAN ADJUST UPWARD if needed. It's a small differnece but may apply here. As I had mentioned in the prio post, it may not have stated the exact details I was pointing out (loss of power and fuel waste when using premium). I'll try to see if I can find the actual consumer report (or other file, thread, etc) that showed it. In any case, this guys post may be similar to the ressults others have experienced.

PS - Personal use. I have a property at Mrytle BEach and have run the exact trip with both premium and regular. The weather conditions were similar (low winds and clear skys) on similar temp days 40-50's (as it was in the winter). The regular actually gave me "slightly better fuel economy (21.3 vs. the premium's 20.8).