Anyone use more than 87 octane gas?

[Armchair Bronco]

I like that I can run my '07 GT AWD with the cheap 87 octane gas, but I'm curious whether anyone has used gas with a higher rating, like 89?

I have to use the expensive 92 stuff with Audi A4 1.8T. If I used 89 with my CX-9, would I notice the difference? Or will it only impact my wallet?

 

[The-9]

I like that I can run my '07 GT AWD with the cheap 87 octane gas, but I'm curious whether anyone has used gas with a higher rating, like 89?

I have to use the 92 stuff with Audi A4 1.8T. If I used 89 with my CX-9, would I notice the difference? Or will it only impact my wallet?

I use 89 in the CX9. Why? Better performance during warm weather. Lower octane, while The 9 will run totally fine, will cause a slight decrease in HP because of the timing being retarded to prevent knocking. Do I see the difference in HP, just a little bit on a long pull, do I feel better about spending 2 bucks more a tankful. yes I do (2thumbs)

 

[Armchair Bronco]

I use 89 in the CX9. Why? Better performance during warm weather. Lower octane, while The 9 will run totally fine, will cause a slight decrease in HP because of the timing being retarded to prevent knocking. Do I see the difference in HP, just a little bit on a long pull, do I feel better about spending 2 bucks more a tankful. yes I do (2thumbs)

Yeah, that's kinda what I was thinking. This may not be something I'll do year around, but if it makes more sense in the summer, then I'm tempted to give a tankful of 89 octane a try for giggles. As you say, it's not ridiculously more expensive than 87, maybe 10 cents a gallon more where I live. My wallet can handle $2.00. (I'll just hold off buying my weekly losing lottery ticket, that's all!)

 

[Force-1]

I use 89 in the CX9. Why? Better performance during warm weather. Lower octane, while The 9 will run totally fine, will cause a slight decrease in HP because of the timing being retarded to prevent knocking. Do I see the difference in HP, just a little bit on a long pull, do I feel better about spending 2 bucks more a tankful. yes I do (2thumbs)

????? The owner's manual clearly states to use 87 octane, so why would it retard timing if you run the recommended 87? I think not.

My C6 Corvette recommends 91, and it will retard timing if I run 89 or 87 in order to prevent knocking since it's designed to use 91 for best performance. Same for my Cadillac STS.

 

[jabba]

Sometimes I think that this engine was designed for higher octane, and Mazda "software-engineered" it to run 87 due to what was happening with gas prices. I have wondered if running a higher octane would actually advance timing so that we get a little bump in HP, but I have just run the 87 stuff ever since we got it.

 

[hamproof]

Higher octane would certainly give a bump in HP. But you are not going to feel it. You might think it has more power from the butt feeling, but in reality, it is probably 2-3hp more. In real world, it is not going to make any difference. It would be better if you loose 10lbs.

 

[semrz1]

Ron 97 CX-9

Well, my 2008 CX-9 is fed with Shell 97. The lowest octance unleaded fuel available in my home country is Shell 92. You will be suprised how much these fuel cost here equivalent to US$0.35 for Shell 97 & US$0.34 for Shell 92. I've tried Shell 92 & definitely a difference in the car performance. My observation with Shell 92 give more fuel mileage but power drops. Opposite to Shell 97, more power but mileage less. In the Mazda Owner manual, it states the minimum requirement is 90 RON. Maybe, different country has different requirement. With US$0.35, what the heck, it's still cheap for me (burnout)

 

[ceric]

Some countries use a different rating system
92 -> 87 (US)
95 -> 89 (US)
97 -> 91 (US)
I don't think 10.3 compression ratio requires high octane gas.
87 actually has higher energy content than 91 per volume. You will see higher MPG with 87 if your engine can run with it by design (not by retarding timing).
MZI 3.5/3.7 was designed from day one to run 87, not an after-thought. You can easily google the web (such as wikipedia) for info.

Feel more power? Placebo effect can be very deceiving.
I would believe a dyno test, though.

Maybe, just maybe, a fully loaded CX9 climbing a hill can benefit from higher octane. However, I have taken my family over sierra mountains. CX9 is quite happy with 87 unlike my old Odyssey which was designed for 91 and ran fine with 87 or 89. I definitely could feel the timing retardation when accelerating hard with 87. Eventually I ran 89 as a good trade-off. To save some $$$ and it actually ran fine with 89 for 8 years w/o a hiccup.

 

[brightwhite]

This is actually completely incorrect. You're actually apt to see a *decrease* in performance. The only time you should use higher octane is if you are experiencing knock. This has been proven time and time again. Google it and you'll see.

The only benefit is the lighter wallet you'll have.

Higher octane would certainly give a bump in HP. But you are not going to feel it. You might think it has more power from the butt feeling, but in reality, it is probably 2-3hp more. In real world, it is not going to make any difference. It would be better if you loose 10lbs.

 

[The-9]

This is actually completely incorrect. You're actually apt to see a *decrease* in performance. The only time you should use higher octane is if you are experiencing knock. This has been proven time and time again. Google it and you'll see.

The only benefit is the lighter wallet you'll have.

Decrease in power when using higher octane? Give me a break and stay away from wiki sites and goof ball sites google may take you too. (boom05)(boom05)(boom05)

While 100 percent of your driving time will be fine with 87 octane, when it gets real hot and humid out, the engine retards timing and richens the fuel mixture based on ambient temps (not based solely on the octane you are using) otherwise your engine will knock. Higher octane lessens that effect of timing retardation a tad since the flame front is a bit cooler which means it can deal with timing being a little more advanced then 87 octane can in that weather condition.

 

[Armchair Bronco]

Bottom line: it *SEEMS* that using 89 instead of 87 will NOT harm your engine, correct?

Therefore, anyone who's interested in this can do their own test and reach their own conclusion using real-world, not anecdotal, evidence.

That's what I plan to do the next time I drain the tank. At worst, I'm out $2.00.

 

[The-9]

Bottom line is 89, 91 or 93 octane will not hurt your engine, PERIOD.

 

[The-9]

My 07 rockets up steep grades on 87, no problem.

It's all relative.

My CX9 is kinda slow when I compare it to my 0-50 5 second SRT10 (dunno)

 

[Force-1]

It's all relative.

My CX9 is kinda slow when I compare it to my 0-50 5 second SRT10 (dunno)

Or my 0-60 4 second C6. (headbang)

 

[benben01]

Or my 0-60 4 second C6. (headbang)

or 1/4 mile in the low 11s in my imaginary GT-R

 

[Force-1]

4 second 0 - 60 doesn't sound as impressive when my 4500lb 7 passenger SUV does it in 7.

Not like my truck, which does it in about 17 seconds.

When you get below 5 seconds it takes enormous power to get quicker times. The new ZR-1 has almost 200 more HP than my coupe, yet is only about .6 seconds quicker to 60. Hell, even the Veyron takes 2.8 seconds, and it has 1000 HP pushing 4100 lbs.

Most of the car mags say the CX-9 does 0-60 in about 8 seconds, and that's the 3.7.

 

[ceric]

Now, we are seriously getting off topic here....
I said "human nature", and someone said otherwise.....
Human!

 

[Armchair Bronco]

FWIW, I just filled up my tank with 89 octane. We'll see what happens. So far, driving only around my neighborhood under 35 MPH, I don't feel any difference. But there are a lot of big hills and highways around here, too. I'll try those next.

 

[tx9]

89 octane for me

I used 87 for the first 8-9 months and got tired of hearing knocking under heavy acceleration. i can't tell a bit of performance or mpg difference, but for me it's worth the extra $2 per tank to not hear that sound. in houston, we have 100 degrees and 90 percent humidity often.

 

[chiurw]

I used regular unleaded gas with 86 octane for a while but noticed the knocking/pinging so I switched to the mid-grade (88 octane) and the knocking/pinging went away.