View Poll Results: OCTANE - Which gas do you put in your 3IS
I always use 91 or higher.
259
91.20%
I sometimes use 89 or 87.
3
1.06%
I always use 89.
6
2.11%
I always use 87.
16
5.63%
Voters: 284. You may not vote on this poll
OCTANE - Which gas do you put in your 3IS and why?(merged threads)
05-04-17, 12:08 PM
#106
No, the full language is in the manual, the manual says "for optimum performance premium fuel recommended". However there is no explanation what optimum performance is, no graphs, no numbers, nothing, hence some of us, born skeptics, after trying different fuels tend to go with "less" than optimum performance (not seeing any meaningful difference in practice). If you feel like using premium fuel - go ahead, it is a free country.
05-04-17, 12:15 PM
#107
On my old Infiniti forum there are countless of threads on this subject dating back years, even though the owner’s manuals also say use 91. But the discussions never seem to end. I hope we’re not going to do the same here. I’m too old for this sort of thing. 
05-04-17, 12:37 PM
#108
And yet, people still ask these questions.
Obviously, price is the ONLY deciding factor between higher fuel grades.
However, people would continue using lower octane and argue that "price is not a factor". Apparently it is.
"$5 is not a concern, but I'm gonna buy the cheaper stuff because I'm a skeptic." BS.
Obviously, price is the ONLY deciding factor between higher fuel grades.
However, people would continue using lower octane and argue that "price is not a factor". Apparently it is.
"$5 is not a concern, but I'm gonna buy the cheaper stuff because I'm a skeptic." BS.
05-04-17, 12:45 PM
#109
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And yet, people still ask these questions.
Obviously, price is the ONLY deciding factor between higher fuel grades.
However, people would continue using lower octane and argue that "price is not a factor". Apparently it is.
"$5 is not a concern, but I'm gonna buy the cheaper stuff because I'm a skeptic." BS.
Obviously, price is the ONLY deciding factor between higher fuel grades.
However, people would continue using lower octane and argue that "price is not a factor". Apparently it is.
"$5 is not a concern, but I'm gonna buy the cheaper stuff because I'm a skeptic." BS.
05-04-17, 12:54 PM
#111
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05-04-17, 01:01 PM
#112
It's just irritating that people are scared of premature engine wear by using low octane and at the same time claim that $5 is not a factor.
I'm being a bit blunt, because I've heard this way too many times.
05-04-17, 01:20 PM
#114
Lexus Champion
I wouldn't use anything less than 91 OCT
05-04-17, 01:27 PM
#115
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So then back to your point, i want to save money. Can I fill up mid grade and still be okay?
05-04-17, 01:28 PM
#116
Lexus Test Driver
Why buy the higher end IS350 with F-sport if you want to neuter the car's performance. Makes absolutely zero sense. $5 isn't worth the concern over pre-mature wear, detonation in engine...etc...etc.. Just use premium as that is the stuff you're suppose to put in. I think most on this forum think its stupid to put in anything under 91 octane.
05-04-17, 01:33 PM
#117
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Why buy the higher end IS350 with F-sport if you want to neuter the car's performance. Makes absolutely zero sense. $5 isn't worth the concern over pre-mature wear, detonation in engine...etc...etc.. Just use premium as that is the stuff you're suppose to put in. I think most on this forum think its stupid to put in anything under 91 octane.
05-04-17, 01:54 PM
#118
05-04-17, 02:01 PM
#119
Pole Position
I think most people misunderstand what octane rating means.
The octane rating of gasoline essentially tells you how much the air-fuel mixture can be compressed before it will spontaneously ignite. Spontaneous ignition is called detonation, also called spark-knock. Spark-knock is an erratic form of combustion that can cause head gasket failure as well as other engine damage. Generally speaking, the higher the engine's compression ratio, the higher the octane required to avoid spark-knock.
With me so far?
Now, considering that our IS 350's have a relatively high compression ratio of 11.5:1, it is this fact, and only this fact, why Lexus engineer's recommend premium octane gas. It is not for fun performance reasons. It is to maintain the normal performance of the engine over a longer period of time.
Using lower than specified octane gas will absolutely damage your engine over time. Period!
Want to verify for yourself? Google "Why different octanes are used" and also google "What causes spark-knock."
The octane rating of gasoline essentially tells you how much the air-fuel mixture can be compressed before it will spontaneously ignite. Spontaneous ignition is called detonation, also called spark-knock. Spark-knock is an erratic form of combustion that can cause head gasket failure as well as other engine damage. Generally speaking, the higher the engine's compression ratio, the higher the octane required to avoid spark-knock.
With me so far?
Now, considering that our IS 350's have a relatively high compression ratio of 11.5:1, it is this fact, and only this fact, why Lexus engineer's recommend premium octane gas. It is not for fun performance reasons. It is to maintain the normal performance of the engine over a longer period of time.
Using lower than specified octane gas will absolutely damage your engine over time. Period!
Want to verify for yourself? Google "Why different octanes are used" and also google "What causes spark-knock."
Last edited by Machine13; 05-04-17 at 02:09 PM.
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