Give mine a good reason why I should...

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daves87rs

daves87rs

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..not run 89 in my cars. I've had a few guys tell me I'm heading for issues or spark knock....though I'm not sure how much of an issue that would be for a four banger (cavalier, Cobalt).

All 3 have improved 3-5mpg

All run/idle much smoother (most noticable in the Cobalt)

Noticed they are a bit peppier..


It seems like they are really cheapening the 87 here to keep the price lower, as I've had a few issues with stations giving me poopy gas. (and we're talking Mobil/ BP, not the no namers)


I've always run some 89 here or there, but I've stuck with just 89 for a month now, and the cars seem to be doing quite well on it.


So, should I stick with it?
 
If money is not an issue for you stick with it. I know mine was acting up on 87 so I gave it 93 for 2 full tanks along with some cleaner and it purrs like a kitten on 87 now.
 
Do the CBA on mileage versus cost. If no, then no, if yes, then yes.

It all comes down to dollars and cents.

Remember, 89 is made by mixing 87 and 93 at the pump...
 
Originally Posted By: daves87rs
..not run 89 in my cars. I've had a few guys tell me I'm heading for issues or spark knock....though I'm not sure how much of an issue that would be for a four banger (cavalier, Cobalt).

All 3 have improved 3-5mpg

All run/idle much smoother (most noticable in the Cobalt)

Noticed they are a bit peppier..

It seems like they are really cheapening the 87 here to keep the price lower, as I've had a few issues with stations giving me poopy gas. (and we're talking Mobil/ BP, not the no namers)

I've always run some 89 here or there, but I've stuck with just 89 for a month now, and the cars seem to be doing quite well on it.

So, should I stick with it?

It seems like you're happy with 89 Octane, there is no reason for not spending extra $1-1.50 per fill up. Just cut down a cup of Starbucks coffee a week is enough to pay for the 89.
 
issues and spark knock? lol!!! to quote Shrek: "What a load of.... "!

Certainly no harm. and, like JZ said, they "make" it by mixing 87 and 93 right at the pump.
 
Depends what the manual calls for...if 87 is required. Run 87. If 93 is required, then run 93. IF 93 is only recommended...then, by all means experiment...including 89.

But all grades of gasoline have the same BTU/gallon...so it's a question of how much anti-knock that particular engine needs...most engine management systems will pull the timing back if the knock sensor is triggered. You won't even know, except that the performance (MPG and power) will decline with retarded timing. So, I run the recommended grade. I notice a slight performance degradation (MPG and Power) with the turbo Volvo engines that recommend 91 if I use 87...
 
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Each car is different, if you are seeing an mpg improvement and your cars are running better on 89, by all means keep doing it.
 
In theory you are wasting your money, in practice it does seem that 87 is not really 87 any more. In quite a few countries the lowest is the 95 RON. Also, with the compression ratio of 9.0 and higher 87 is not really going to work despite all the tune trickery. By the law they are all required to run on regular here, does not mean they are designed for such. On v8 modulars from Ford, midgrade is demonstrably better.
 
In all my engines that require regular i use the mid grade most of the time because it is a little faster and it does not boarderline a ping condition that you may not be able to hear without a listening scope
 
Originally Posted By: HTSS_TR
Originally Posted By: daves87rs
..not run 89 in my cars. I've had a few guys tell me I'm heading for issues or spark knock....though I'm not sure how much of an issue that would be for a four banger (cavalier, Cobalt).

All 3 have improved 3-5mpg

All run/idle much smoother (most noticable in the Cobalt)

Noticed they are a bit peppier..

It seems like they are really cheapening the 87 here to keep the price lower, as I've had a few issues with stations giving me poopy gas. (and we're talking Mobil/ BP, not the no namers)

I've always run some 89 here or there, but I've stuck with just 89 for a month now, and the cars seem to be doing quite well on it.

So, should I stick with it?

It seems like you're happy with 89 Octane, there is no reason for not spending extra $1-1.50 per fill up. Just cut down a cup of Starbucks coffee a week is enough to pay for the 89.



Good point. All 3 are paid for, so I'm not sweating the few extra bucks out of a 13 gallon tank or so.



Guess I might have to cut down on the K cups though...
grin.gif
 
contrary to popular opinion and my owners manual I absolutely get better mileage with premium fuel in my 2AZ-FE. it can vary valve timing but I'm not so sure on spark timing. Anyway, she runs beuatifully on premium, smooth idle, great response (for a camry). When i switch to regular and moreso E10, she goes rough again.

I don 't have irrefutable evidence and I am sure someone will say it's placebo.
 
Originally Posted By: crinkles
contrary to popular opinion and my owners manual I absolutely get better mileage with premium fuel in my 2AZ-FE.

The same story here on 2UZ-FE.
 
I'd use it....if the car seems to be performing better, keep on with it...

That, or if cost becomes an issue, perhaps compare the prices of other "over the counter" octane boosts, and see what has more cost savings for you; getting the extra "AKI" from the pump, vs. getting it from a 2-4$ bottle....I hear the "104" product by Sta-bil, IsoHeet, etc. is a very good product, but it is quite pricey.....at the ~$4 mark, but then there's GumOut and/or STP at the $1-3 range.....

BTW, is that car specd for 89 AKI?
 
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After reading this post I am going to try a tank of mid grade gas today when I fill up. I think the midgrade at 7-11 is 91 octane. I know it was 14 cents more per gallon yesterday on their sign out by the road. I am willing to spend a couple of extra bucks to see if there is any improvement. I am going on about a 40 mile round trip today so I hope to have at least some butt-dyno results to post when I get home.
 
I filled up with 15 gallons of 89 octane at 7-11 today. My truck does feel like it has a little more power, it was a little easier to gun the throttle up a hill in 5th gear and it felt like it was running a bit stronger. The idle was very smooth. For me this is by no means a definite answer on the mid grade gas, though. I need to run this tank out and maybe another one too before I know for sure if it helps power or not. Same with MPG, I have no way to really tell until I fill up again. I will post back here when I have more results.
 
Originally Posted By: lexus114
Originally Posted By: ltslimjim
The old Civic's manual specifies 86 octane.



Thats why I said almost.


It's all good. I could've said the same thing you did too, I just thought it was cool regarding this car is all.
grin2.gif
 
I've seen some engines with >11:1 compression call for 87.

The deciding factor might be how fast the computer changes the ignition advance curve to compensate for the higher octane.
The higher octane didn't seem to make any difference on my Grand Prix engines/computers. The new Terrain may be quicker to adjust.
We'll see.

The difference in price seems about the same as it has been for some time. If they've cheapened the 87, it's to improve the profits, as if they aren't making enough already.
 
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