Premium Fuel Recommended

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Hey everybody,I am not trying to beat a dead horse here.But the search on here is not so great. Anyway, What is the real deal using regular fuel,in a vehicle that claims: select 87 octane.For best performance,the use of 91 octane or higher is recommended. That is what it states in my manual. I know the ecm adjusts timing etc, but doesnt that make the engine run hotter? And it already is a sludge prone motor to begin with. Or is this perfectly ok to do?, and just won`t have the extra power? I do understand that a vehicle that requires premium, Mercedes-Benz etc. You don`t have a choice. But to tell you the truth,this is confusing,and I cant get a straight answer anywhere.

Ryan
 
If your car specs premium fuel only,I`d heed that advice. I put regular unleaded in my first 300ZX turbo I had,and I got detonation. Some cars have to have it and some don`t.
 
Thanx for the quick response,My 2001 RX 300 only states recommended. So,I am just trying to find out if it will harm the motor in the long run.I have 100,000 miles on it now,bought it with 77,000 and used premium most of the 1 1/2 I`v owned it. I do notice it isn`t as responsive on regular,(And I have reset the ecm) But I am also Thinking fuel will rise again this summer,and every penny help`s when it`s $4.00 a gallon.
 
Originally Posted By: Steve S
Reduced performance. As dad would say "why did you buy a car like that"


I like the RX very much, But I was asking myself about my decision when I was @ the gas station last summer,when fuel prices were over 4 bucks a gallon. Everyone else was pumping regular unleaded,I on the other hand was not.
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A lot of new vehicles CAN run regular but recommend premium.
Read the owners manual carefully.
Supercharged GMs will run ok on regular; but if you like the performance, premium is the way to go.

If you can run without detonation, it's up to you.
You could, as least, get by with mid-grade if you keep your foot out of it.
 
The computers on most newer cars will retard the timing if regular fuel is used. This will keep the engine from having detonation, but will cost some performance.
You could always run mid grade and split the difference.
Your MPG may suffer from running regular, but it still might be cheaper depending on the cost of premium.
 
I wonder if running premium would be better since the ethanol content is much less. Ive heard some folks do notice a slight difference, ive haven't done any experimenting yet.
 
I thought ethanol increases octane, so premium could have more ethanol.

Anyway, I read the "Select 87 octane. For best performance, the use of 91 octane or higher is recommended" to mean just what it says: 87 works just fine, but 91+ will give you full performance potential.

Why don't you try two tanks in a row of each? If you notice no difference in fuel consumption and performance then continue to use 87.
 
Our previous Subaru outback recommended premium fuel. It tended to get 91+ when I filled it and 87 when my wife did.

No significant difference in MPG, smoother idle with premium only difference noticed.
 
Originally Posted By: lexus114
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Hey everybody,I am not trying to beat a dead horse here.But the search on here is not so great. Anyway, What is the real deal using regular fuel,in a vehicle that claims: select 87 octane.For best performance,the use of 91 octane or higher is recommended. That is what it states in my manual. I know the ecm adjusts timing etc, but doesnt that make the engine run hotter? And it already is a sludge prone motor to begin with. Or is this perfectly ok to do?, and just won`t have the extra power? I do understand that a vehicle that requires premium, Mercedes-Benz etc. You don`t have a choice. But to tell you the truth,this is confusing,and I cant get a straight answer anywhere.

Ryan



Ryan,

If what you say is true then the manual is saying that you can use 87 octane BUT you can use higher for better performance. The main thing is it doesn't ping on you.

My manual says basically the same thing. For economy I'll use 87 all then time for 98% of my driving needs.

If I were you I'd use 87 in the same manner as I and go higher perhaps for long trips and such.

Durango
 
I will mention the performance is much better on the premium.Of course it is getting older now (2001) 100,000k etc.So it would benefit from the higher octane anyway.I am going to see how it performs on the 89 octane fuel,only because I believe our 93 octane here is simply overkill.I`ll Let you know what I discover.
 
My Lincoln LS requires 91+. I use 93 octane. One day I had to put 87 in it due to the last station on the highway being out of high octane.

That is the last time I do that. Car ran bad, and my MPG dropped 10%!
 
Quote:
I like the RX very much, But I was asking myself about my decision when I was @ the gas station last summer,when fuel prices were over 4 bucks a gallon. Everyone else was pumping regular unleaded,I on the other hand was not.
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Thats a common sentiment - to be more concerned about having to buy premium when gas prices are high. But when gas prices are high, premium gas makes less of a difference.

Around here it is 20 cents more per gallon for premium. If gas is $2/gal it raises the cost by 10%. When gas is $4/gal, it only raises it by 5%.
 
My 2001 Honda Odyssey recommends premium but says you can run 87. They say you get 205 hp on reg, 210 on premium. I have tried both, cannot tell the difference, so I have only run 1 or 2 tanks of premium, and it has 120,000 miles on it. In later years Honda recommends only regular, I think they still think premium is better, but customers are happier with the recommendation of regular.
 
Originally Posted By: ksJoe
Quote:
I like the RX very much, But I was asking myself about my decision when I was @ the gas station last summer,when fuel prices were over 4 bucks a gallon. Everyone else was pumping regular unleaded,I on the other hand was not.
smirk2.gif



Thats a common sentiment - to be more concerned about having to buy premium when gas prices are high. But when gas prices are high, premium gas makes less of a difference.

Around here it is 20 cents more per gallon for premium. If gas is $2/gal it raises the cost by 10%. When gas is $4/gal, it only raises it by 5%.


up here in Quakervania,it`s around a 30-35 cent difference between reg.and prem.
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Originally Posted By: John K
My 2001 Honda Odyssey recommends premium but says you can run 87. They say you get 205 hp on reg, 210 on premium. I have tried both, cannot tell the difference, so I have only run 1 or 2 tanks of premium, and it has 120,000 miles on it. In later years Honda recommends only regular, I think they still think premium is better, but customers are happier with the recommendation of regular.


John,in mine I can tell the difference; More pep,smoother idle,better mpg,and some claim that the air-flow sensor`s last longer on premium. Probably due to a cooler exhaust temp.Now that I look at this,I think I`m answering my own initial question.
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And it even affects the shift quality.
 
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My family had a '97 Avalon with the same engine as your RX. We used Premium exclusively and never had problems. You have a very solid car despite the year and mileage. In fact the Lexus is just getting broken in. I have a '99 Nissan Maxima and use Premium as recommended by the owner's manual for maximum performance. Don't let the mileage and year scare you as your vehicle has a lot of life in it left. Sensors may have a shorter lifespan in a vehicle designed for premium that uses regular.

Continue with Premium in your Lexus as it cannot afford reduced performance in a heavy vehicle fitted already with a relatively small V6.
 
Will everybody forget about ping or knock or preignition? In a modern engine that will only happen if one of the control components is defective or if carbon build up in the combustion chamber glows red hot and ignites the fuel charge before the spark fires.

A couple of years ago "Car & Driver" magazine tested several cars on a dyno. They found that using regular in an engine designed for premium gas resulted in less power, higher consumption, no fuel cost savings, and no problems. Using premium in an engine designed for regular resulted in no power increase, no consumption changes, no problems, and a waste of money.

lexus114, try each type of fuel for at least three repeatable tankfuls each, figure your total fuel cost per mile (not just miles per gallon), note the driving feel, and decide which fuel you prefer.
 
My 4.6 SOHC V8 in my 96 Crown Vic has no knock sensor and knocks like crazy on anything less than 91 octane. I also get better fuel mileage on premium.
 
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