View Poll Results: OCTANE - Which gas do you put in your 3IS
I always use 91 or higher.
![](https://www.clublexus.com/forums/images/polls/bar2-l.gif)
![](https://www.clublexus.com/forums/images/polls/bar2.gif)
![](https://www.clublexus.com/forums/images/polls/bar2-r.gif)
![](https://www.clublexus.com/forums/clear.gif)
259
91.20%
I sometimes use 89 or 87.
![](https://www.clublexus.com/forums/images/polls/bar3-l.gif)
![](https://www.clublexus.com/forums/images/polls/bar3.gif)
![](https://www.clublexus.com/forums/images/polls/bar3-r.gif)
![](https://www.clublexus.com/forums/clear.gif)
3
1.06%
I always use 89.
![](https://www.clublexus.com/forums/images/polls/bar4-l.gif)
![](https://www.clublexus.com/forums/images/polls/bar4.gif)
![](https://www.clublexus.com/forums/images/polls/bar4-r.gif)
![](https://www.clublexus.com/forums/clear.gif)
6
2.11%
I always use 87.
![](https://www.clublexus.com/forums/images/polls/bar5-l.gif)
![](https://www.clublexus.com/forums/images/polls/bar5.gif)
![](https://www.clublexus.com/forums/images/polls/bar5-r.gif)
![](https://www.clublexus.com/forums/clear.gif)
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)
#136
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Interesting Video on fuel...
#137
Intermediate
iTrader: (1)
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
From personal experience of using both Mid and Premium, you actually get slightly better highway MPG when using premium. I used to use premium for long trips and switched back and forth to mid in city driving sometimes. If you have to use midgrade, it wouldn't hurt but you wont get maximum potential out of the 350 engine. Just DO NOT use regular. I wouldn't recommend it.
Last edited by GibbsLexus; 07-19-17 at 01:58 PM.
#138
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
From personal experience of using both Mid and Premium, you actually get slightly better highway MPG when using premium. I use premium for long trips and switch back and forth to mid in city driving sometimes. If you have to use midgrade, it wouldn't hurt but you wont get maximum potential out of the 350 engine. Just DO NOT use regular. I wouldn't recommend it.
For a 14 gallon fill, that's a massive $2 difference. Even if you drive a lot and fill up every week, that's an extra $8 a month.
I really don't get these people. Buys a $45k+ car and wouldn't spend the extra $2.
#139
Lexus Test Driver
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Why even bother using 89 mid grade? The difference is usually 0.15c per gallon!!!
For a 14 gallon fill, that's a massive $2 difference. Even if you drive a lot and fill up every week, that's an extra $8 a month.
I really don't get these people. Buys a $45k+ car and wouldn't spend the extra $2.
For a 14 gallon fill, that's a massive $2 difference. Even if you drive a lot and fill up every week, that's an extra $8 a month.
I really don't get these people. Buys a $45k+ car and wouldn't spend the extra $2.
Unless your car is leased, then I would understand not caring much. But for you owners out there, use the premium.
#140
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
I don't know how many of these threads I've read over the years......
This is a simple question of CAN vs. SHOULD.
Can a car that recommends 91 run on lower? Yes. Probably with a small hit to mileage and power. Modern engines are all equipped to deal with knocking.
Should you? No. Because as the data provided in this thread indicates, year after year forcing your engine into an off-nominal mode to deal with knocking rages somewhere from "most likely" to "will" damage your engine over time. But then several people always chime in and say, "I've used 87 for years and years and never had a problem." To that I say just because someone hasn't had a problem doesn't yet mean they will.
To me it's very simple. Go with what the people who designed the engine say. Car manufacturers are not out there conspiring to force people to buy expensive gas. It's engineering and science. If price isn't an object, there is no reason at all to take on the risk. If cost is an issue, you shouldn't be driving a Lexus.
This is a simple question of CAN vs. SHOULD.
Can a car that recommends 91 run on lower? Yes. Probably with a small hit to mileage and power. Modern engines are all equipped to deal with knocking.
Should you? No. Because as the data provided in this thread indicates, year after year forcing your engine into an off-nominal mode to deal with knocking rages somewhere from "most likely" to "will" damage your engine over time. But then several people always chime in and say, "I've used 87 for years and years and never had a problem." To that I say just because someone hasn't had a problem doesn't yet mean they will.
To me it's very simple. Go with what the people who designed the engine say. Car manufacturers are not out there conspiring to force people to buy expensive gas. It's engineering and science. If price isn't an object, there is no reason at all to take on the risk. If cost is an issue, you shouldn't be driving a Lexus.
The following 2 users liked this post by 1Louder:
GibbsLexus (07-19-17),
zhifan1 (07-19-17)
#141
Intermediate
iTrader: (1)
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
My same exact thought.. why bother trying to save that extra buck or two for midgrade. Just get the premium. Buys 50k car, and goes cheap with gas. Cmon bruh.
Unless your car is leased, then I would understand not caring much. But for you owners out there, use the premium.
Unless your car is leased, then I would understand not caring much. But for you owners out there, use the premium.
#142
drives cars
![](https://www.clublexus.com/forums/images/ranks/rank-mod2.gif)
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
my TRD Toyota solara V6 gas cap says "unleaded fuel only" reason why I stay positive because it's a big different between the regular fuel and the premium fuel , I've learnt this 16 years ago. I put regular it drives fine but pulling sucks like 4cyl corrola. And then I had to replaced knock sensor after 2 years of running regular cost me 350$ oem sensor. Yes it's up to drivers though. Regular fuel sometimes makes the car jerking what I've experienced .
Looked up the owner's manual. It says:
OCTANE RATING
2AZ−FE engine: Select Octane Rating 87 (Research Octane Number 91) or higher.
3MZ−FE engine: Select Octane Rating 87 (Research Octane Number 91) or higher. For improved vehicle performance, the use of premium unleaded gasoline with an Octane Rating of 91 (Research Octane Number of 96) or higher is recommended.
Use of unleaded gasoline with an octane rating or research octane number lower than stated above will cause persistent heavy knocking. If it is severe, this will lead to engine damage.
2AZ−FE engine: Select Octane Rating 87 (Research Octane Number 91) or higher.
3MZ−FE engine: Select Octane Rating 87 (Research Octane Number 91) or higher. For improved vehicle performance, the use of premium unleaded gasoline with an Octane Rating of 91 (Research Octane Number of 96) or higher is recommended.
Use of unleaded gasoline with an octane rating or research octane number lower than stated above will cause persistent heavy knocking. If it is severe, this will lead to engine damage.
Note, this is about the Solara. Don't go putting regular in your IS.
![Wink](https://www.clublexus.com/forums/images/smilies/wink.gif)
#143
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
OP just get fuel rewards and when you go about your normal business you earl 5-20 cents per gallon as you shop of visit stores. Buy the end of a typical month you could have up to $2 off on a gallon up to 20 gallons. t-mobile just did a promotion with them that saved me $25 on gas so there are many other ways to save money on gas without buying the dino-pee that is 87-89 octane. By the way mid grade is just premium and regular mixed 1/2 and 1/2. It's litterally cheaper to just put 1/2 of tank of 87 and half 93 to make your own 89 in the tank
![Smilie](https://www.clublexus.com/forums/images/smilies/smile.gif)
#144
Pit Crew
iTrader: (1)
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
what if you get free gas? would you guys still put them in? the octane rating is unknown since i salvage them from junk cars. i save at least 100 a month on gas, in fact, i never go to gas station for gas ever since i got the car lol i know that it will ruin my engine in the long run, but what the hell.. free gas!!!! i have a Fill-Rite fuel pump with water block filter to transfer all my gas. i tried to only salvage from cars that run premium gas, but still you can't tell if the owner actually used premium. that's why i use chevron fuel injector cleaner every 1000 miles to prevent issues in the long run.
my 200t is at 26k mileage now and i don't notice any performance decrease. i always drive in sport mode and aggressive to push out all the carbon lol besides, i don't care about gas mileage.
what do you guys think? should i continue using these salvage gas?
my 200t is at 26k mileage now and i don't notice any performance decrease. i always drive in sport mode and aggressive to push out all the carbon lol besides, i don't care about gas mileage.
what do you guys think? should i continue using these salvage gas?
#146
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
what if you get free gas? would you guys still put them in? the octane rating is unknown since i salvage them from junk cars. i save at least 100 a month on gas, in fact, i never go to gas station for gas ever since i got the car lol i know that it will ruin my engine in the long run, but what the hell.. free gas!!!! i have a Fill-Rite fuel pump with water block filter to transfer all my gas. i tried to only salvage from cars that run premium gas, but still you can't tell if the owner actually used premium. that's why i use chevron fuel injector cleaner every 1000 miles to prevent issues in the long run.
my 200t is at 26k mileage now and i don't notice any performance decrease. i always drive in sport mode and aggressive to push out all the carbon lol besides, i don't care about gas mileage.
what do you guys think? should i continue using these salvage gas?
my 200t is at 26k mileage now and i don't notice any performance decrease. i always drive in sport mode and aggressive to push out all the carbon lol besides, i don't care about gas mileage.
what do you guys think? should i continue using these salvage gas?
#147
drives cars
![](https://www.clublexus.com/forums/images/ranks/rank-mod2.gif)
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
what if you get free gas? would you guys still put them in? the octane rating is unknown since i salvage them from junk cars. i save at least 100 a month on gas, in fact, i never go to gas station for gas ever since i got the car lol i know that it will ruin my engine in the long run, but what the hell.. free gas!!!! i have a Fill-Rite fuel pump with water block filter to transfer all my gas. i tried to only salvage from cars that run premium gas, but still you can't tell if the owner actually used premium. that's why i use chevron fuel injector cleaner every 1000 miles to prevent issues in the long run.
my 200t is at 26k mileage now and i don't notice any performance decrease. i always drive in sport mode and aggressive to push out all the carbon lol besides, i don't care about gas mileage.
what do you guys think? should i continue using these salvage gas?
my 200t is at 26k mileage now and i don't notice any performance decrease. i always drive in sport mode and aggressive to push out all the carbon lol besides, i don't care about gas mileage.
what do you guys think? should i continue using these salvage gas?
![](https://cimg6.ibsrv.net/gimg/www.clublexus.com-vbulletin/200x197/694_3ff1fcb29d7cf8daef71b74e940c5a4ac9aab182.png)
The following users liked this post:
UngBuck (07-20-17)
#148
Pole Position
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
All Lexus IS model’s engine’s specified Fuel Octane Rating is 91 or higher for optimum engine performance and lifetime.
If 91 octane cannot be obtained, you may temporarily use an octane as low as 87.
Use of an octane rating lower than 91 may result in engine knocking, rough idle, noisy engine sounds.
Persistent knocking can lead to expensive engine damage, or worse…
Avoid or correct the above issues by refueling with higher octane gasoline.
^-- partially quoted from our owner’s manuals.
BTW, never tell the dealer you used anything less than the specified gas. Or.... be the good Samaritan and fess up to your mistake.
If 91 octane cannot be obtained, you may temporarily use an octane as low as 87.
Use of an octane rating lower than 91 may result in engine knocking, rough idle, noisy engine sounds.
Persistent knocking can lead to expensive engine damage, or worse…
Avoid or correct the above issues by refueling with higher octane gasoline.
^-- partially quoted from our owner’s manuals.
BTW, never tell the dealer you used anything less than the specified gas. Or.... be the good Samaritan and fess up to your mistake.
![Banned](https://www.clublexus.com/forums/images/smilies/banned2.gif)
#149
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
I'd be willing to bet what you experienced was real. I had the same car during the span of time in WA state when we went from ethanol free to E10, and I was tracking my MPG with every tank. E10 dropped my MPG by ~10% (and I had years of data on either side of the change). Of course E10 is all I can get now. So I was able to quantify some inefficiency, but a small change in performance is more of a butt-feel thing.
#150
Driver
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
I may be a bit late, but it's not accurate to refer to octane in terms of grade (what it costs, or quality) or level, or type.
Octane is not a substance, or a level of distillation accuracy, or an additive.
It's a comparison between the fuel you're buying and 100% iso-octane as to a single property: knock resistance. 100 is equal, 99 is less, 70 is too much less.
That's all it does, it's not "better" or "different" in any way (except as specified).
If you don't need it, it's just money wasted since it contains less thermal energy per gallon than low octane. Using CAM2, Sunoco 116, etc. is wasting money for any production car ("but it feels faster": that's your lighter wallet).
If your sonic knock-detection system and its spark retard work well (IDK how long they last) the ECM will adjust to lower octane by making the car slower at (nearly) WOT.
Octane is not a substance, or a level of distillation accuracy, or an additive.
It's a comparison between the fuel you're buying and 100% iso-octane as to a single property: knock resistance. 100 is equal, 99 is less, 70 is too much less.
That's all it does, it's not "better" or "different" in any way (except as specified).
If you don't need it, it's just money wasted since it contains less thermal energy per gallon than low octane. Using CAM2, Sunoco 116, etc. is wasting money for any production car ("but it feels faster": that's your lighter wallet).
If your sonic knock-detection system and its spark retard work well (IDK how long they last) the ECM will adjust to lower octane by making the car slower at (nearly) WOT.