Why Premium Gas

[gwilson]

The Toyota Sequoia appears to have the same 470 engine as the GX 470. Regular gas is recommended for the Sequoia while regular is acceptable but premium is recommended for the Lexus. Since the compression ratio is the same on both engines and the Sequoia is rated 5 hp more than the Lexus, why use premium in the GX470?

[Reggie]

I have been through about a half-dozen tanks of fuel since buying the GX.

In town commuting and highway cruising I cannot tell the difference between regular and hi-test.

It's when I hook up the 5,000# trailer that premium gas seems to be important.

[denslexusgx470]

careful when using premium, becuz it happened to me once that i upgraded to premium for a while, then came to california, shocked by gas prices, downgraded to unleaded, created a engine ping.

[strindl]

careful when using premium, becuz it happened to me once that i upgraded to premium for a while, then came to california, shocked by gas prices, downgraded to unleaded, created a engine ping.

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Could that have just been the specific brand of regular that you tried that may have been substandard? I can't think of a reason why it would make a difference if you switched back and forth.

I havn't tried 87 octane regular yet, but have noticed no difference between 92 octane prem, and 89 octane mid grade. How many others have tried experimenting with different grades of gas, and with what results?

[GS400jon]

careful when using premium, becuz it happened to me once that i upgraded to premium for a while, then came to california, shocked by gas prices, downgraded to unleaded, created a engine ping.

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Could that have just been the specific brand of regular that you tried that may have been substandard? I can't think of a reason why it would make a difference if you switched back and forth.

I havn't tried 87 octane regular yet, but have noticed no difference between 92 octane prem, and 89 octane mid grade. How many others have tried experimenting with different grades of gas, and with what results?

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I have only used 87 octane in the GX and haven't had any problems. Tried 89 octane for six months on the ES330, then went to 87 octane with no problems and no noticeable difference in performance or mileage. I use Shell gasoline for both vehicles.

[denslexusgx470]

careful when using premium, becuz it happened to me once that i upgraded to premium for a while, then came to california, shocked by gas prices, downgraded to unleaded, created a engine ping.

←

Could that have just been the specific brand of regular that you tried that may have been substandard? I can't think of a reason why it would make a difference if you switched back and forth.

I havn't tried 87 octane regular yet, but have noticed no difference between 92 octane prem, and 89 octane mid grade. How many others have tried experimenting with different grades of gas, and with what results?

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well, we can consider it like this, consider coming from earning , oh maybe $1m a year, then downgrading to 500k a year, well it's hard to adjust, so i guess it's the same thing for cars. (just an example!) ;) especially that previous car of mine was used to premium for the first 80k, then moved to ca, downgraded to 87 from 92, had an engine ping!

[pagemaster]

With my Tundra I can see a big difference between 87 octane and 91.

I have been using 91 for a while now and I get a little better gas mileage which I believe offsets the increased costs. The truck just feels like it has more torque when I run 91.

Are there any differences between the Tundra/Sequioa 4.7 and the LX470, GX470, 4runner?

I think there are some differences. For one, my parents have a 4runner with v8 and the way it is bolted in the engine bay is a littler different with the air filter and such. Another thing, the Tundra's spark plugs are the cheaper kind compared to my parents 4runner. The plugs on my truck only last till 30K or something like that while the 4runner's last longer.

Whether or not these differences are the reason for the truck needed premium is beyond me.

I am also convinced that my Tundra really does require premium but Toyota says it doesn't to keep pickup buyers still interested. I am sure the die hard pick up guy who REALLY needs a pickup for the farm will be pretty turned off when he finds out he needs premium. So Toyota just says, regular.

[DKRC-2003]

Keep in mind that gas companies "tweak" the additives that they place in fuels not only in different parts of the country, but during differnet parts of the year as well.

I do not know for sure, but with all the other regulations that Callie places on motor vehicles, I'd be willing to bet that the fuel additives in CA are drastically different than elsewhere.

All makes for many different sets of variables on why engines run differently...

[SKperformance]

Moved to the general maintance forum

as this is another commonly asked question that is not vehicle specific.

[vcv10guy]

with my ES300 i noticed there is a difference in octane. i used 87 and the mileage was okay, when i jumped to 89, the fuel mileage dropped. the weird thing is though, i changed to 91 then the fuel economy was better all of sudden. it seems my car hates 89. i'm just sticking with 91 and using Shell gasoline.

[DKRC-2003]

A friend of mine used to be an engineer for Exxon in Houston....

According to her, the mid-grade (i.e. Unleaded Plus) is nothing more than the low and high grade octane fuels blended together...

It has been a while since we talked about all of this, but I remember it being fascinating, might have to shoot her an email and post the reply to everyone.

Anybody got any questions that they would like to ask an Exxon Engineer about?