Regular Gas

[Nash04]

Hey! Everyone.

My friend bought her CX-7 about month ago has been using only regular gas and never had any issues so this weekend I filled up with regular gas and had no issues as of yet! which already have put over 200 miles on the first tank. The performance is the same but noticed the gas mileage to be a slight better 1 mpg with air and 60/40 hwy/city. So I'm going to fill up again next time with regular and see what happens. Her husband did fill up with premium one time and she noticed the performance was not as good. Perhaps Mazda's last ECU upgrade change our settings to accept regular gas.

 

[SuperStretch18]

High compression + turbo means I will be using high octane. If it works for you; go for it, but I am way to concerned with detonation.

http://en.wikipedia.org/wiki/Engine_knocking

Quote:
"The cylinder pressure rises dramatically beyond its design limits and if allowed to persist detonation will damage or destroy engine parts...Engine knocking has disastrous consequences for the engine, since it leads to the catastrophical wear of the combustion chamber walls, through particle wear for moderate knocking, to welding for serious knocking. This is due to the contact between those walls and high temperature gases resulting from the unwanted explosion. The processus also lead to a 'knocking' noise for the engine, that give its name to the phenomenon..."

 

[B1GHAM]

(rofl2)

lets all buy a vehicle that requires premium and fill it with regular!!

its like $2 a tankfull more to use premium and there is a reason it runs on premium. superstretch is completely correct.

no the ECU change was not to make you run on regular fuel either. I also call bs on any performance claim towards regular gasoline.

 

[mikey1981]

i will just say, that if you are unfortunate enough to experience detonation in this vehicle, then you are in for one wild ride. It was among the many symptoms of my lemon, and I will say this, just for safety's sake...use premium. the cars computer shuts the engine off - regardless of speed - to protect itself. It happened to me a few times on the highway and if not for any other reason, spend the 4 bucks a tank and possibly save thousdands in the future and or avoid an accident or any other harmful situation. it is not that big of deal in hindsight. (my detonation was not because of low grade gas - but it was detonation none the less and i never want it to happen again)

 

[Nash04]

Totally agree with you all but it's kind of funny that she has over 3,000 miles and haven't had any issues. As for myself, I'll more likely go back to Premium since I've been running it since the get go and this was only the first time that I use regular gas and still had a quarter tank of premium when I did use it.

 

[offset_98]

Just sell the car...I think the Mazda 6 takes regular.

 

[CX-7owner]

Totally agree with you all but it's kind of funny that she has over 3,000 miles and haven't had any issues. As for myself, I'll more likely go back to Premium since I've been running it since the get go and this was only the first time that I use regular gas and still had a quarter tank of premium when I did use it.

Although she might not have any problems now, she will later. And the cents shes saving on regular over premium really wont matter and may cost her more when shes paying for the repairs. When the car says 91 Required, take it seriously, If she didn't like the idea of paying premium gas she should have gotten in a rav4 or something. Shes damaging her car. Believe it or not.

 

[HeavyH20]

Hmmm, it is possible that the mileage improvement is because the turbo is on vacation with regular gas. The car goes into a limp mode so you can operate, but it should definitely not get the same performance. It may feel the same, but if you measured it, there would be a significant difference.

 

[S_T]

typical modern day engines have intetgrated knock sensors. These sensors will typically trigger an safemode algorithm in the ECU to 1) increase fuel 2) retard timing 3) reduce boost, or a combination of all the above. while you can conceivably get away without damaging your engine under these circumstance (the stock manual does say it is okay to run it w/ 87, albeit temporarily), you performance wil suffer because the anti-knock content of 91+ is much greater.

I think people are too anal about what others do...its your car, you choose as you will and be responsible accordingly. Heck on my hobby car, an Evo 9, I run 100 octane only!

 

[Nash04]

Now this is all here say! She stated that when her husband uses Premium gas, she noticed a lost of power but on the next regular fill up, her performance was back. Also be aware when Motor Week tested our vehicle, they tested it with regular gas, now this could have been a typo on their part but usually when the vehicle stipulates that you must use a certain gas, they would usually state so but did not. Talk about weird!

 

[Grantman]

lol

 

[1Sleepy93]

When the CX goes into limp mode the max throttle opening is limited to 30% and it also sucks some timing off amoung other things.

mikey, I had detonation problems early on with my CX but after a few flashes it's been taken care of.

 

[mikey1981]

When the CX goes into limp mode the max throttle opening is limited to 30% and it also sucks some timing off amoung other things.

mikey, I had detonation problems early on with my CX but after a few flashes it's been taken care of.

ahh im happy to hear that - i honestly wish it never happened, im still waiting on the new one to arrive

 

[1Sleepy93]

Sorry to hijack here.

ahh im happy to hear that - i honestly wish it never happened, im still waiting on the new one to arrive

So are they giving you a new CX or replacing the motor?

 

[mikey1981]

new CX, clone of my other one in white on beige

 

[Rick's CX-7]

typical modern day engines have intetgrated knock sensors. These sensors will typically trigger an safemode algorithm in the ECU to 1) increase fuel 2) retard timing 3) reduce boost, or a combination of all the above. while you can conceivably get away without damaging your engine under these circumstance (the stock manual does say it is okay to run it w/ 87, albeit temporarily), you performance wil suffer because the anti-knock content of 91+ is much greater.

I think people are too anal about what others do...its your car, you choose as you will and be responsible accordingly. Heck on my hobby car, an Evo 9, I run 100 octane only!

This and sleepy are the only posts that make any sense and are on the right track.
I have used 87 numerous times and never had any problems. I think mileage dropped slighty though, but other than that, no problems. The manual does say transmission shift will be affected....but I didn't notice anything.
A lot of you guys like to jump in this hysterical bandwagon and scare the crap out of everybody. Yes, 91 or higher is recommended, but for 87 to destroy an engine, numerous things, not just gas, would have to come together and cause a chain reaction. With a drive-by-wire, I wouldn't be surprised if the PCM takes completely over as soon as detonation sets in....reducing timing, adding fuel and closing the throttle.

 

[HeavyH20]

Of course, all new engines adapt. That is why it is "recommended" gas versus required. Using it occasionally will not cause any issue, but long term effects can be negative in high compression/forced induction engines. I think that is all anyone has ever said. It is not like a single fill up of regular will grenade your engine. The engine simply retards engine performance by trimming timing advance and boost. Depending on whether or not it was an open loop versus closed loop ECM solution, you might see some issues on the first time you "stomp" the accelerator. You simply loose performance. I also wonder if this "trimmed" performance lead the first poster to actually see better mileage? We all know the turbo is the enemy of fuel efficiency. So what happens if it limits itself to 8 lbs boost with low octane gas? Better mileage? Maybe.

 

[gsrtype1]

dude your lucky its disi that helps but with high compression and turbo it compounds the dangders of detonation , i love my car tomuch to risk it!

 

[SuperStretch18]

Feel free to use what ever gas you want people, but for me it will be premium all the way. Same way that I won't push back an oil change, just to save some cash. It won't immediately trash your engine, but what impact does it have long term?

You can make your own cost/benefit analysis, but I hope that this car will run 200k miles for me. A primary reason that I bought it was due to it's performacne; if I was worried about a couple of dollars extra at each fill-up, I would have bought something else.

Do whatever you want, just don't cry "mazda sucks" and bring down all of our resale values when you need engine work at 100k...

 

[singlemalt_18]

Don't sweat the small stuff

I can only chuckle a bit as I continue to see all this concern about gasoline and costs. As the price of a gallon of gas has increased over the years, this debate about premium over regular becomes a red herring. Here is why:

When gas was $1.00 a gallon, premium was $1.20. This meant there was a 20% cost increase to burn the good stuff.

When gas was $1.50 a gallon, premium was $1.70. It was then a 13.3% cost increase to run the high octane.

At $3.00 a gallon for 87 octane, the price difference PER GALLON is still about TWENTY CENTS! So in fact, it is now only about 6.5% more expensive to run what the manufacturer recommends.

At 20,000 miles per year, and 18 average mpg, your using 1,111 gallons a year. At $0.20 a gallon that $222 a year or $18.50 a month, or SIXTY CENTS A DAY!!!!!

If all you can afford is 87 octane, perhaps you can't afford a car?