fahody

hi guyz
i just bought my new GS430 2008 yesterday

my freind told me to fill it with super ultra fuel which is octine 98
i filled it with fuel octine 95

what do u advice me to do ?
my freind told me octine 95 will harm the engine in the long run
do i need to put octine 98 or its just better to ?

flipside909

Go with what your owners manual recommends. Here in the US, Premium Unleaded (91 octane or better) is required for the 08 GS350, 450h and 460.

rominl

iTrader: (4)

yes, just stick with the factory spec

trusso

is your 98 octane unleaded?

litesoarer

Should have gotten the 460, lol.....unless you got some wild discount on the outgoing 430.

Be wary of those super high octane fuels, as they may contain lead. The highest octane i can recommend is Sunoco 94 (if available in your area)

caha14

In the US, octane at the pump is the average of "RON" and "MON" (research octane number and motor octane number). The 95 you are pumping is likely 95 RON, which as the excerpt from Wikipedia below shows is borderline (90 to 91 US). Lexus requires 91 in the US - that is, 91 PON (pump octane number, average of RON and MON), so you probably need 98 to play it safe. Do check your manual to see if octane numbers are adjusted to the proper measure.

Look at the red text below.

Congrats on your new car, by the way!

Measurement methods
The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing these results with those for mixtures of iso-octane and n-heptane.

There is another type of octane rating, called Motor Octane Number (MON) or the aviation lean octane rating, which is a better measure of how the fuel behaves when under load. MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally fuel specifications require both a minimum RON and a minimum MON.

In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-92 in Europe. However most European pumps deliver 95 (RON) as "regular", equivalent to 90-91 US (R+M)/2, and even deliver 98 (RON) or 100 (RON).

The octane rating may also be a "trade name", with the actual figure being higher than the nominal rating.[citation needed]
It is possible for a fuel to have a RON greater than 100, because iso-octane is not the most knock-resistant substance available. Racing fuels, straight ethanol, AvGas and liquified petroleum gas (LPG) typically have octane ratings of 110 or significantly higher - ethanol's RON is 129 (MON 102, AKI 116) reference[1]. Typical "octane booster" additives include tetra-ethyl lead, MTBE and toluene. Tetra-ethyl lead is easily decomposed to its component radicals, which react with the radicals from the fuel and oxygen that would start the combustion, thereby delaying ignition. This is why leaded gasoline has a higher octane rating than unleaded.

mysteryan

Stick with 91, sounds like the only thing it hurts is your wallet. I've tried race fuels in my other cars before (100 octane), but I never heard of anyone filling entire tanks with it.

caha14

He's in Kuwait... Octane #s are measured differently.

Yang1815

iTrader: (1)

caha14 is correct. The octane rating is different. Just use 98.

As for litesoarer, they only offer 430 in Kuwait.

okcfunky

Absolutely unnecessary to run beyond minimum manuf. spec. unless you like to throw money for sheer sport.
I forgot the translation between various octane measures.

fahody

so guyz what do u really advice me of ?
we have here octine 95 and 98
still confused

caha14

Read the information we've given you! If your manual does not say what you should do, we've already told you:

1. 95 in Kuwait is equivalent to between 90 and 91 in the US. The US model requires 91, so putting 95 will probably work for you even if it is (technically) a bit less.

2. If you want to play it extra safe and don't mind the extra $, put in 98.

The G Man

Here is a article from 2005 for the Austrialian version of the GS430. It states minimum fuel grade is 95 RON for the GS430.

http://www.webwombat.com.au/motoring...430-review.htm

valgs350

iTrader: (1)

Well when my GS was at 10k I put 100 octane and went to Irwindale, on a hot day it feels faster on a cold day it feels the same!!!

but

I don't put 100 octane anymore, only twice + its a waste of money 7.67 a gallon...lol