b1gredek

i was just wondering if the gs300 really require premius fuel, i was thinking if the supra non turbo doesnt,, why does the gs require it..... i have always been using premium,,,,, just thought i find a conclusion... since i dont have a manual, i cant confirm that it does require premium

Canyonero

all Lexus require premium.

Leets

but why? If the Supra doesn't take premium then what's so different about the timing, compression, etc. on the 2jz-ge in the GS? I'm curious now, too.

b1gredek

this is exactly why i asked this question......

e-diddy

I am not sure if premium is required on the GS or any other Lexus model for that matter, but I go with it all the time anyway. I know that gas prices are through the roof, but if you can afford it, why not give it to our rides.

If I could afford it, I would eat at Ruth Chris Steak House instead of fast food every day for lunch.

Just a thought..........

ebruce2

iTrader: (1)

personally, I don't even bother to question it. For the amount of money you might actually save over a year of buying cheaper gas, I consider it an insurance policy for my vehicles. All of my vehicles get at least 93 OCT, even my POS 1996 Jeep Cherokee.

GS300Rich

I just spend the extra money on the 93 and dont worry about it. The savings is minimal, but if you add it up over a whole year it could be a few hundred $. But to me it isnt worth it.

sockfocks

iTrader: (1)

OK...the GS300 requires premium fuel because of ONE reason...10.5:1 compression ratio (at least on the 1999 year) A supra engine turbo-charged (someone correct me if i'm wrong) is at 8.5:1 compression ratio. Fuel is more likely to detonate or cause preignition in high compression engines. Thats why our engines require premium fuel. With higher octane fuel you can run higher cylinder pressures and more advanced timing without running into "knock" which is pre-ignition. If you run 87 octane in your GS the ecu will compensate and retard the timing which will reduce efficiency and power and mileage. No reason or logic to run 87 in a GS unless its the only gas station within 300 miles and its the only gas you can get.

jonathancl

Fuel energy content has nothing to do with octane; you are only wasting money on higher octane fuel.

Using higher octane gas than required by the engine only makes it more difficult for the flame-front to flow quickly and gracefully from the plug to the piston head.

Using lower than required, on the other hand, can result in preignition (where the fuel ignites before the spark plug fires) or detonation (where the entire mixture explodes together when the spark plug fires). Both subject the cylinder to much higher temperatures than normal combustion and will damage the engine.

If the engine pings (which is caused by two flame-fronts created at the same time, one by the piston and the other by the spark plug, which come together and entinguish each other) and requires higher than recommended octane to silence the pinging, your engine is running too hot and needs maintenance.

If the engine runs smoothly at its recommended octane, it's foolish and unnecessay to change it.

If the enging requires 91 octane, as the 3uzfe does, that's what you should give it, no more, no less.

Leets

but "premium" fuel isn't any better/cleaner than "regular." Octane rating only relates to the gasoline's ability to combust unignited under certain pressures.

Si2See

I used premium 93 the first month I had my lexus and it got worse mileage than when I tried 87 so thats what I have been running and have never ever had one single problem.

Alexus-Kia

i use the middle gas # dont know what oct. level it is, so i guess thats bad!!

sockfocks

iTrader: (1)

lol

lexusondubs

iTrader: (9)

yes it is in the manual it states USE PREMIUM UNLEADED FUEL ONLY !!!!!!!!!

GRAND_LS 4

iTrader: (2)

It really doesnt matter if the engine is shared by other cars, its more along the lines of whats programmed in the ECU. Its all about the ECU when i comes to octane.