Lexus IS Forum banner

21 - 40 of 82 Posts

·
Registered
Joined
·
43 Posts
What if I use 93 octane on my '01 IS300? I swear by Sunoco petro and I hardly use any other gas station besides that solely because its one of the few, if any, that still has 93 octane. Will there be any negative side effects from using a even more refined fuel level? :)

Kudos,
Jay
 

·
Registered
Joined
·
5,052 Posts
What if I use 93 octane on my '01 IS300? I swear by Sunoco petro and I hardly use any other gas station besides that solely because its one of the few, if any, that still has 93 octane. Will there be any negative side effects from using a even more refined fuel level? :)

Kudos,
Jay
Using a higher than required octane fuel will do nothing (compared to just using the required octane) other than maybe cost you more money.


The only thing octane means is resistance to knock. If your car doesn't knock on Octane X than running Octane X+ provides no benefit whatsoever.
 

·
Registered
Joined
·
2,095 Posts
I still don't think I understand..
While I agree with most of the above, there are different levels of knock.

the knock sensor, as stated above safeguards the engine from knock by retarding the ignition and adding more fuel, this lowers fuel economy.
At the level the knock detector can hear I do not believe there is any damage being done, at the level where we can hear it yes there is potential damage, the first being melted or damaged piston crowns. Longer term piston land damage and maybe rings.

My pathfinder has "Premium preferred" rating , and most on the Nissan forums run regular, as I do, and have no damage in hundreds of thousands of miles.
Does it make a difference at end of life of the engine ? maybe.

My daughters 86 Audi 4000CS had 450K on it, engine never touched, and was still running great. we brought from first owner who was a friend. Yes i had to twist their arm to sell it to me.
Maybe with modern engines its not a factor.
Why do engines fail ?
Number one reason ( from a Toyota dealer and shop for older Toyota's ie not new dealership) leaks causing engine to run dry or hot !!! Mainly Oil leaks.
Turbo it and then its a different story, spun bearings seem number one !!!
 

·
Registered
Joined
·
7 Posts
Just to Piggyback off JayMarino i do think that using 89 vs 91 octane may cause a knocking because i didnt always use 91 and when gas got outragous i started using 89 gas from base and my car did start knocking.. i didnt know that gas could have an effect like that. I would normally use a fuel boosting suplement but guess that didnt help too much.. HEy jaymarino do you know if the knocking will go away????
 

·
Registered
Joined
·
5,052 Posts
Just to Piggyback off JayMarino i do think that using 89 vs 91 octane may cause a knocking because i didnt always use 91 and when gas got outragous i started using 89 gas from base and my car did start knocking.. i didnt know that gas could have an effect like that. I would normally use a fuel boosting suplement but guess that didnt help too much.. HEy jaymarino do you know if the knocking will go away????


The definition of "octane rating" is the rating of the fuels resistance to knocking.

If you want the engine to not knock, use fuel of the required octane. It's that simple.


(and the "octane booster" you see in stores is crap.... when it states it raises octane "8 points" you might wish to be aware each "point" is 0.1 octane. So it turned your 89 into 89.8.
 

·
Registered
Joined
·
8 Posts
I noticed on a bottle of octane booster it said it raises it 10 pts which would raise it from 89-90.

So if i use the lowest octane available and add the octane booster, it will still do damage to the engine?

I was under the impression that if the engine doesnt knock using lower octane than premium, than it isnt damaging it? Although you would loose a little power..
 

·
Registered
Joined
·
5,052 Posts
I noticed on a bottle of octane booster it said it raises it 10 pts which would raise it from 89-90.
Correct... 10 "points" would raise it 1 octane.

So if i use the lowest octane available and add the octane booster, it will still do damage to the engine?
Yeah, because it's only raising it from 87 to 88 (87 being the lowest octane generally available) and the engine is designed to run on 91.

I was under the impression that if the engine doesnt knock using lower octane than premium, than it isnt damaging it? Although you would loose a little power..

You should always run on the lowest octane with which the engine never knocks.

For an IS that is 91, because that's what it's programmed to use from the factory. That's what the compression and timing are intended for.

Less than that and it will knock at some point (probably under load, when it's warm, or some combination of conditions... probably not when it's just sitting there idling).

You might not HEAR it do so, and your knock sensors will then pull timing to stop it pretty quickly... then gradually add it back... then it'll knock again, and repeat the cycle... doing a very tiny bit of damage each time.

The pulling of timing is where you "lose power" (or mileage in many cases, more than negating the 10 cent/gallon savings)

On the other hand, running anything higher won't help you at all.
 

·
Registered
Joined
·
114 Posts
ok so i mistakenly put 87 in my tank. i know if i use an octane booster that wouldn't really help raise the rating. what if i use up 1/4 of the tank and put in 100 octane. would that compensate at least through the rest of the tank? noob question i know...
 

·
Registered
Joined
·
2,095 Posts
unleaded 100 octane ?
add octane booster allowed for unleaded fuel, you should be able to raise it up.
 

·
Registered
Joined
·
5,052 Posts
ok so i mistakenly put 87 in my tank. i know if i use an octane booster that wouldn't really help raise the rating. what if i use up 1/4 of the tank and put in 100 octane. would that compensate at least through the rest of the tank? noob question i know...
First thing I'd say to do- drive the car easy... no mountain climbing or racing.

If you have unleaded 100 octane available (the stuff many tracks have isn't, and it'll mess up your cats) then your idea would put you up to ~90 octane... of course it's not evenly mixed in the tank, but it'd be better than nothing.

Honestly, over a single tank, if you take it easy driving, the handful of times it might knock then pull timing aren't going to do much harm... it's when people drive like that for thousands (or tens of thousands) of miles that they might come to regret it (or the next owner surely will).
 

·
Registered
Joined
·
8 Posts
Knightshade, thanks for the info about the knocking issue. I thought it would be a knock that I could hear.

My work allows me to fill up for free on-site BUT we only have regular gas. No premium on hand..

I have an 03 IS300 that I just bought. Its been dealer serviced since new and has 90k miles on it and i dont want to do any damage to the engine.

Should I stock up on octane booster and put 4 bottles in each tank? That would put me at about $15 bucks per fill-up. Is that too much octane booster?

The free gas is a perk of the job and I'd hate to miss out on it BUT i dont want to damage my engine.
 

·
Registered
Joined
·
5,052 Posts
Knightshade, thanks for the info about the knocking issue. I thought it would be a knock that I could hear.

My work allows me to fill up for free on-site BUT we only have regular gas. No premium on hand..

I have an 03 IS300 that I just bought. Its been dealer serviced since new and has 90k miles on it and i dont want to do any damage to the engine.

Should I stock up on octane booster and put 4 bottles in each tank? That would put me at about $15 bucks per fill-up. Is that too much octane booster?

The free gas is a perk of the job and I'd hate to miss out on it BUT i dont want to damage my engine.


Heh... well, if you're going to need to bump your octane ALL the time you might want to look into making your own booster using toluene (which is often used for this purpose in race fuel)... it'll be a lot cheaper just be careful handling the stuff.

toluene is 114 octane, so 1.5 gallons per 8.5 gallons of 87 octane fuel would give you 91.05 octane. (depending on the actual booster formula used these #s might change a bit, but gives you a ballpark... that's a lot of additive though)

I'm not sure if adding that much of either OTC booster or home-made stuff would be especially easy on emissions components and other sensitive bits, especially if used every single tank over a long period of time (versus once in a while at the track).

Personally, were it my car, and I wanted to keep it a very long time, I'd skip the 87 (or trying to Frankenstein 87 into 91).
 

·
Registered
Joined
·
114 Posts
thanks knightshade! +rep for you sir for helping me out and explaining the octane ratings. my local 76 gas station sells 100 octane stuff (at almost $9 a gal) but i have never seen if it was leaded or not. i guess i'll have to check it out.
 

·
Registered
Joined
·
95 Posts
im surprised not to see sunoco on the top tier list i've been using it for years now. - Since I got my IS a few weeks ago, I tried sunoco and bp - i only been using sunoco since - but thanks to this post i have to find a shell near me.
 

·
Registered
Joined
·
5,052 Posts
im surprised not to see sunoco on the top tier list i've been using it for years now. - Since I got my IS a few weeks ago, I tried sunoco and bp - i only been using sunoco since - but thanks to this post i have to find a shell near me.
Won't make any difference whatsoever.

Nor have I ever seen anyone provide credible evidence that "top tier" gas works any better than the name brands that don't pay to get in on the marketing scheme.

USA today wrote a story about this a while back, that included this bit-

A twice-yearly gasoline-quality survey by the trade group Alliance of Automobile Manufacturers "hasn't identified any quality differences based on geography or brand," says Alliance spokesman Charles Territo.
More quotes from the story-

"I see these ads on TV where Shell says, 'We filled up with Shell and some other gasoline and saw a difference,' and I think it's a myth," says Thomas Darlington, engineer and consultant at Air Improvement Resource in Novi, Mich., and formerly at the EPA.
"It's hype," says Dennis DeCota, executive director of the California Service Station and Automotive Repair Association. "It would be very hard to differentiate" among brands.
"I really look at these commercials and wonder, 'How do these guys justify this?' I don't see the benefits," says John Frala, who teaches auto mechanics at Rio Hondo College in Whittier, Calif. He says he's never seen a breakdown due to engine deposits.

This isn't to say you won't run into the Smiley Brand gas in some little town one day and it sucks... or that you won't buy gas from a name brand station (even a top tier one) that has a leaky underground tank with water seeping in.

It is to say there's no need to pay extra for "top tier" though, in general any other major name brand will perform as well if it's the same octane.
 

·
Registered
Joined
·
96 Posts
basically 91 octane is the minimum....These engine were designed originally to run on 95 octane as japanland not only has better cars but better gas as well...
If you run less the engine will just retard the timing to prevent pinging and detonation..

MOre timing increases cylinder pressure which in turn produces more power, and the opposite is true as well.....
 

·
Registered
Joined
·
5,052 Posts
basically 91 octane is the minimum....These engine were designed originally to run on 95 octane as japanland not only has better cars but better gas as well...
They really don't.

Japan uses a different octane rating system than the US.

In the U.S. gasoline is described in terms of its "pump octane", which is the mean of their "RON" (Research Octane Number) and "MON" (Motor Octane Number).

In Japan they display RON on the pumps.

So 95 octane (RON) in Japan is roughly 90-91 octane under the US system.
 

·
Registered
Joined
·
96 Posts
nope been in japan 3 times.....motors def designed for the ron equivalent of 95 octane...

I know what mon vs ron is..... That would explain why alot of jap spec cars certain lack of emissions control devices..

Now briefly lets keep it a hundred... Literally...Designed for 100 RON or 95 octane....
My japanese compadres are yota gurus and always said the same thing...
In fact alot of the altezzas I saw on the gas door said 100Ron...
and that was the point that I asked wtf is Ron?
Japan and Europe use a system called RON or Research Octane Number to determine the octane rating of their gasoline, while stateside we use a system called AKI or Anti-Knock Index to determine gasoline's octane rating... Interestingly, to further complicate things it would seem that our own AKI system is actually derived from the average of the RON system and another more complicated system referred to as MON or Motor Octane Number... So, to recap our methodologies for measuring gasoline's octane rating are different, but share some common elements...
So, with the commonality of RON in mind a good rule of thumb is as follows, multiply the foreign RON Octane rating by 0.95 and you will have the US AKI equivalent.

( RON Octane Rating x 0.95 = AKI Octane Rating )
98 RON Octane x 0.95 = 93.1 AKI Octane (US measure)
100 RON Octane x 0.95 = 95 AKI Octane (US measure)
 
21 - 40 of 82 Posts
Top