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Discussion Starter · #1 ·
The owners manual says octane 91 is required or engine damage may occur. Is this really true? Can you run on 89?
 

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you really should only be running what it says to be running...
It's an the owner's manual, obvioulsy there is a reason for that. The car will underperform on anything less and you will end up screwing up your fuel system
 

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Yes I believe it is necessary. I had a friend who has a nissan maxima, it says in the manual that it consumes 91 octane or higher, and he didn't put the 91 once, he said the engine is making some wierd performance, so he changed back to premium, and now the car is running well and strong again.
 
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As Altersys says, it has to do with the compression ratio of the engine.

Higher compression also means higher heat. Higher octane gasoline can withstand higher temperatures. If you use an 87 octane at a higher compression, the heat from the high pressure can ignite the gasoline before the spark plug fires. So, if your pistons are firing before they are supposed to, that is not good for your engine.

If the manual says to use premium, then you should. That's what the engined was designed for.
 

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The rule of thumb is, you should use the lowest octane gas that will prevent your engine from knocking. The compression of the engine will determine how high of an octane gas is needed to prevent knocking.

Owner manuals will recommend this octane. You can use higher octane gas, but you will be basically wasting money. If you use lower octane gas, you may find lower performance. If you use too low of an octane, the engine will start knocking (or pinging), which will eventually lead to engine damage.

I guaratee if you start having problems with the engine after using lower octane gas, any mechanic will tell you to use higher octane gas.

If you damage your engine because you used lower octane gas, you will probably get hassled by the dealership if you try to get a warranty claim.
 

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Re: not so fast

gobuds said:
check out the link below, recently on the front cover of USA Today, great article, I think it is true. My wife's MDX calls for 91 and we use mid-grade, never had a problem.

http://www.courier-journal.com/business/news2003/07/31/biz-3-gas31-4431.html
Engine compression will determine what octane gas you should use in your vehicle to get the maximum performance.

The article even states that using a lower octane gas will yield lower performance... although they go on to state that in most cases you will not notice the difference.

I'm willing to bet if you measure the HP of your MDX on a dyno while running on mid-grade then on premium, you'll see a difference. With every day street driving, you probably won't "feel" the difference, especially with an SUV like the MDX. If you're not having any problems with mid-grade, why don't you try regular unleaded?

With the TSX, you might actually feel the difference if you go with a lower octane, as the engine has a higher compression than the MDX, and most TSX owners will probably drive it a little more aggressively than an SUV.

The rule of thumb is you won't go wrong with following the owner's manual.
 

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the TSX manual says 91 octane is required, not
recommended. There is a difference. The 3.2TL
says recommended, not required, so 89 will work
on the standard model TL (Type S, 91 is required)
so I suggest you use the 91 octane on your TSX.
 
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It looks we might need Acura to clarify this premium gas question. In the official USA "2004 Acura TSX" brochure (page 26 under "General Specifications"...Recommended Fuel), footnote 8 states that "Gasoline with an octane number lower than 91 may be used, with reduced performance."

I've never seen the owners manual....but if it says premium is required, there is definitely a discrepancy.
 

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moslof said:
It looks we might need Acura to clarify this premium gas question. In the official USA "2004 Acura TSX" brochure (page 26 under "General Specifications"...Recommended Fuel), footnote 8 states that "Gasoline with an octane number lower than 91 may be used, with reduced performance."

I've never seen the owners manual....but if it says premium is required, there is definitely a discrepancy.
The car will probably run fine with gas that has less than 91 octane, but you will get less HP and MPG.
 

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sjlee said:
The car will probably run fine with gas that has less than 91 octane, but you will get less HP and MPG.
Not to mention pinging, retarded timing, and increased emissions (which may also put a strain on your catalytic converters). Honda engines are tuned to the edge of performance. Don't mess with that formula.

-Alt
 

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Discussion Starter · #14 ·
Thanks for all the responses. Don't know where you all are at, but in Northern CA, premium gas is going for $2.35.
 

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spinstr said:
Thanks for all the responses. Don't know where you all are at, but in Northern CA, premium gas is going for $2.35.
:eek: OK, I think I will stop complaining now. Premium in north Mississippi is ~$1.80 and everyone is crying about it.
 

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Just filled up with Sunoco Ultra 94. Low sulfur content and contains ethanol...therefore leaves less deposits and burns cleaner.
 

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spinstr said:
Thanks for all the responses. Don't know where you all are at, but in Northern CA, premium gas is going for $2.35.
so you'd rather buy cheaper gas now and have your engine break later? :rolleyes:

I live in Nor Cal too.
 

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STC said:
so you'd rather buy cheaper gas now and have your engine break later? :rolleyes:

I live in Nor Cal too.
Agreed. Pinging on a high compression engine is not a good thing. Granted, the TSX engine is programmed to retard timing in the case of "bad gas" but you can't plan for every possibility. Take for example a really hot day...

Spend the extra cash on good gas, or don't buy a premium-level car.

-Alt
 
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