flipside909

I have to disagree w/that one. Even though the 3GR-FSE is high compression, there are instances in different elevations that you actually get better mileage with lower octane fuels. This is true with the 1MZ-FEV6's w/10.5:1 c/r.

DaveJ

I'm waiting on delivery of my GS300. Does the manual recommend 91 or 93 octane?

bigzip

The owners manual says use 91 octane or better but if such premium type cannot be obtained you may temporarily use a rating as low as 87.

DaveJ

Thanks again bigzip. 91 is what I expected and that's what I'll be using.

bitkahuna

iTrader: (20)

It has to say 91 and up (instead of 93) because you can't get 93 in CA I believe.

flipside909

That is correct. Premium here in CA is 91 octane. 89 for Mid and 87 for Regular.

my06GS300

I guess, this will help you to understand why you need a higher octane gasoline for your Lexus.

http://www.howstuffworks.com/question90.htm

If you've read How Car Engines Work, you know that almost all cars use four-stroke gasoline engines. One of the strokes is the compression stroke, where the engine compresses a cylinder-full of air and gas into a much smaller volume before igniting it with a spark plug. The amount of compression is called the compression ratio of the engine. A typical engine might have a compression ratio of 8-to-1. (See How Car Engines Work for details.)
The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.
The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.
The name "octane" comes from the following fact: When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you may have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.
It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.
During WWI, it was discovered that you can add a chemical called tetraethyl lead to gasoline and significantly improve its octane rating. Cheaper grades of gasoline could be made usable by adding this chemical. This led to the widespread use of "ethyl" or "leaded" gasoline. Unfortunately, the side effects of adding lead to gasoline are:
• Lead clogs a catalytic converter and renders it inoperable within minutes.
• The Earth became covered in a thin layer of lead, and lead is toxic to many living things (including humans).
When lead was banned, gasoline got more expensive because refineries could not boost the octane ratings of cheaper grades any more. Airplanes are still allowed to use leaded gasoline, and octane ratings of 115 are commonly used in super-high-performance piston airplane engines (jet engines burn kerosene, by the way).

rominl

iTrader: (4)

yup that's correct, here in cali we only get 91 unless you get race gas. and actually 91 is classified as premium already. putting even higher octane wont' hurt anything, you just kinda "waste" a bit to certain extend

jarrett

When gas prices first started to rise, I tryed 89 octane in my 1993 GS. And i guess it did o.k for a while but i had just got off of the dan ryan express way and while i was bagging into my drive way i pulled it out to straighten up, and all of a sudden it cut off, and then it started right back up.

My advice is to u is to pay a little extra because in the long run you'll save big bucks.

nortrack

Reading this thread with interest, however, would you you guys consider cost as a major influencing factor in this decision if you were paying UK gas pump prices.....

Currently 1 Litre = £0.91 or 1 Litre = US$1.72

That works out at US$6.52 a gallon!

Yes that's what we are paying for gas at the pump here in the UK/England.......

Anyone want to fill up here?

rominl

iTrader: (4)

the question should not be how much a gallon of gas cost over there. the question should be, what's the difference on prices between different grades of gas. if the gap is somewhat like what we have here, about 10 cents each grade, then i don't see any reason to go with anything lower than premium. you have a 50k car to begin with (and in UK it's a lot more expensive too )

nortrack

For me it won't be an issue, our GS will rightly get the premium grade, but man I wish we could pay your prices just to fill the tank up with anything!

bitkahuna

iTrader: (20)

Ugh - that's terrible. What a burden on people there. It's amazing so many can cope with it (and high prices n general). I was born and raised there but don't miss those prices! And the M25 is still a parking lot a lot of the time.

Do you guys know the U.K. has a 17.5% sales tax!?! It's already 'built in' to prices (you never see it at cash registers).

maddiec

I recently purchased a 06 gs300 rwd a few weeks ago. Great Car!! It is recommended to use premium fuel on this automobile ( which I do). But, I keep hearing that 87 grade fuel is just as good and I'm wasting my money on the 91. Need your opinions.

Thanks.

rominl

iTrader: (4)

there is a difference. our cars need 91+ fuel. with 87 it's ok, but the computer will retard its timing, and maybe you will get some pinging as well

just get 91. if you can afford the car you can afford the gas. overall using 91 you will spend like 200 bucks more a yr?