Regular Gas for 2008 CX7

[chillum]

I read in the car and driver or road and track SUV review for 2008 that the 2008 cx7 now has premium fuel 'recomended' rather than required after a computer 'update'. Is that true and can we get that for a 2007 CX7?

Also if we ask for the latest flash does that include all the previous updates?

What should I ask for? ECM, TCB? All the terms are confusing..

Thanks for the help!

[erhayes]

91 Octane fuel is still the recommended fuel for the 2008 MY. Using less than 91 octane will cause lower performance, possibly poor shift quality and reduced provability. If you can't afford to put the recommended fuel in the car I'd recommend buying a car that recommends 89 or 87 octane fuel. The TSBs are for the TCM & the ECM. Are you having issues with your transmission or engine? If not, then why brother with the TSBs? In addition: the TSBs are related to the build date & VIN #.

[chillum]

I am having hesitation off the line and the 5/6 gear shift issues. I did confirm that my car falls in the VIN range and build date.

I also have been averaging about 13.5 miles over the first 3500 miles with mainly city driving 85%. I was hoping they made an adjustment on the fuel requirements where it would not change performance.

In Miami the difference can be upto 40 cents per gallon. I was just curious if we still needed to put premium in it based on the article i read.

I realize I can always get a new car, its not an affordability issue. That line of 'buy another car' is overused when discussing this topic it seems. Why does that have to always be the only response? Rich people don't buy $25,000 Mazdas.

But thanks for the help.

[erhayes]

Go to the Mazda owners web site and look at your owners manual. The section that comments on fuel octane lists some of the issues you will/may experience if you choose a lower than recommended fuel. People in AK run their CX7s on the highest octane fuel available which is 90 octane. I would never ever run less than 89 except in a real emergency. Didn't mean to be condescending with my comment about getting a vehicle you can afford to run. Just seems foolish to buy a vehicle, knowing what the required or recommended fuel is and then have issues with an extra $3 per fill up. I too grit my teeth at the gas companies prices and in my case, I choose to curtail my driving mileage and use the 91 recommended. JMW. Ed

[chillum]

I was just hoping that it was no longer a requirement. The problem I have is that the salesman told me 'off the record' it was just a reccomendation and that you could run regular. Then I a couple days after taking delivery I find out that it is a requirement and that if you use anything else it may void the warranty! So I guess my displeasure stems from that. I agree that over all with my low annual mileage (3500 miles in 7+ months) its not a big deal. I was just wonderingif anyone had any more info than the blurb I read. Hell we pay over 5$/gallon for bottled water and oer 8$/gallon for starbucks so whats an extra 40cents right!

[astraelraen]

A friend of mine who works at the dealership we bought out 2007 CX7 from last July said their GM has a 2007 CX7 and has run it with nothing but 87 for almost a year.

He bragged about it enough that I would guess their salesmen might use that pitch if someone balks at the premium fuel required/recommended label for the CX7.

I'm not condoning it or saying that it doesn't run like crap. These are the kind of statements that are coming out of Mazda's sales side though.

I've never tried anything less than 91. At our altitude I could probably get away with 89, but I wouldn't try 87. But in reality, the cost savings from 91 to 89 are <2 bucks. So its not that big of a deal. Now if we could get off the winter mix and raise my 15mpg in the winter....

[YelPro03]

This is exactly why I didn't get the CX7. I was getting rid of a car that required premium so I wasn't about to get another one that requires it too. Gas is expensive enough as it is and I don't need to pay an additional $.30/gallon.

[erhayes]

The sales side of the dealership has an agenda-TO SELL CARS-PERIOD. Not saying they always lie but, it is my money so I do my homework before consulting a dealer. I am averaging 21.57 mpg with my 07. I use 91 or higher as some of my staions premium is 93. When I get 93 I will fill with 89 when down to ~ 1/2 tank. JMW Ed I enjoy my vehicle very much and bought knowing 91 was required and expecting to get the EPA rating as I always have in the past. I am exceding the EPA new estiments and could have easly bought a vehicle that uses 87 octane but only got 16 mpg so performance wise & mileage I am $$ ahead.

[MSTswamp]

It is only costing me an extra $208 annualy to burn 91 octane over 87 octane. I am averaging about 16,000 miles a year. Why bother with the cheap stuff. Keep the 91 octane in it. Performance Man! ZOOM ZOOM

[kleung]

No one has answered the simple question OP asked: whether a shop or a dealer can tune the 2007 engine to make it same as the 2008? It's a simple technical question. Can someone who knows just answer it without all the judgemental stuff?

[erhayes]

I have read second hand that Mazda stated that there were engine modifications in addition to modifying the ECM software. The 2008 option can't be made retroactive to 2007. I do not remember the manual saying that 87 octane was OK, but that 91 was now recommended rather than required. Mazda has stated that the lastest software updates include ALL previous updates so if you get the ECM & TCM updates you will have it all. TMC=transmission control module and ECM=engine control module. Good kleung?

[Rick's CX-7]

chillum,

I have run 87, 89, 90, 91 and 93 octane in my 2007 CX-7 (built June 06) and this is what I've seen:

1- Under heavy and repeated WOT runs, I did not notice any knocking/pingin using the lower octane fuels; even in the hottest summer months.

2- Under heavy and repeated WOT, there was a very subtle hesitation, as if the engine had hit the rev limiter. I theorize the computer saw something it didn't like and either closed/open the throttle repeatedly and/or took/added timing and/or fuel. This doesn't necessarily mean the computer detected imminent destruction.....just something it didn't like.

3- Transmission shifting was not affected at all.....at least that I could sense.

4- Fuel mileage was mixed! It seems during the summer months, the higher octane got better MPGs. During the cold months, the lower octane seemed to have done better at times. At times, no matter what fuel I used and what time if the year it was, I got just about the same.
Now, Miami is my hometown, and if you haven't experienced cold other than Miami's, then you don't know what cold is. I'm now living in Missouri, where is much colder than the coldest day in Miami. Running a lower octane in the cold months in Miami might not have the same effect as in Missouri.

5- If maximum performance is desired, I do suggest running 93 octane. For normal and moderate driving, 87 or 89 did just fine.


I caught a lot of heat for doing this and reporting my findings here; so I'm risking going through it all over again.

Rick

[astraelraen]

I caught a lot of heat for doing this and reporting my findings here; so I'm risking going through it all over again.
Rick

OMG RICK WE'RE GOING TO KEEEEEEL YOU AND UR CX7 WILL DIE A HORRIBLE DEATH

:eek:

Thanks for the info :)

[Shaz]

I don't even bother to find out what the lower octane gas can do to my "new addiction"....she is fed prime/premium/ultimate/exceptional GAS. The difference in savings won't make me buy a mansion. If I'm stingy about money I would just have bought a Kia Rondo or a Chevy Aveo.

JUST ENJOY THE "Zoom-Zoom" while getting stares from the Interstate audience. Live it...love it.

[erhayes]

Interesting observations Rick's CX7: I would have expected that the lower octane fuel ( 87) would show prononced performance degrdation at WOT but, much less at easy driving. I have two questions Rick. 1. did you run 2 or more tank fulls of the same octane one after another for your test? or did you go from 91/93 to 87 so you got a mix? 2. Did you find a difference in the brand of fuel used i.e. Shell/Chevron/BP etc. vs no name?

[Mazda3]

To echo what was said above, there is more than a PCM program to make the 08's run on regular, there were some mechanical changes as well. So the changes can't be made to the 07 without great expense.

[Rick's CX-7]

Ed,

I ran numerous tanks of 87 and 89 consecutively for hundreds of miles, without interruption. Again, never experience any knocking/pingin.....just that hesitation I mentioned under heavy WOT, where the ECM seemed to have slightly closed the throttle. This did NOT happen all the time either.
Interestingly, the only time EVER that I've got pinging was just 3 days ago, running 93 Mobil gas. I stepped on the gas from a 25-30mph roll and the engine pinged, then bucked and then took off normally. The tranny was in auto mode. First time this engine has hiccuped liked this.

Rick

[erhayes]

Ed,

I ran numerous tanks of 87 and 89 consecutively for hundreds of miles, without interruption. Again, never experience any knocking/pingin.....just that hesitation I mentioned under heavy WOT, where the ECM seemed to have slightly closed the throttle. This did NOT happen all the time either.
Interestingly, the only time EVER that I've got pinging was just 3 days ago, running 93 Mobil gas. I stepped on the gas from a 25-30mph roll and the engine pinged, then bucked and then took off normally. The tranny was in auto mode. First time this engine has hiccuped liked this.

Rick Makes me wonder why the insistance of Mazda with the 91 min. requirement on the 07. Could there be an issue with carbon build up over time or some other issue I can figure out? I may try a tank of 89 and see if my 07 does ok. I know they sell AK CX7s that run on 90 as that is the best availiable. Ed in SW FL.

[Rick's CX-7]

I should also mention that I have been running 93 since 3 months ago. I've decided to stick with it for the time being. I may run 87/89 again without hesitation though.

I would encourage other people to try 89 and report back to us. One car is just not enough data to prove/disprove anything!

[erhayes]

Running my 07 on a top tier 89 octane Shell fuel now. I suspect that problems will be magnified when using a heavy throttle in manual mode. The AT is more forgiving by not being able to lug the engine or even load too heavy without downshifting. presently I'm driving normal i.e. 20000--3000rpm shifts using the AT. Will report after 3 tank fulls (325 miles/tank) or less if issues arise. Ed

[Rick's CX-7]

Ed,

I am confident you could step on it until you put a dent on the floor without problems. If there is one thing I've learned about these cars is that the ECM has a lot of power over most functions, including the throttle. If it sees anything at all, it will close the throttle.

[erhayes]

presently running a mix of 1/4tank 91 octane and 3/4 tank of 89 Chevron. No issues during normal light to medium throttle driving. Will keep you updated Rick. Ed

[chillum]

I got the latest recalls, Computer Update and swirl valve. The truck is much smoother off the line. Mileage still sucks at 14 around town light driving. Premium is now 344/g

It costs about 20-25 cents per mile to drive this thing

[CX7_Scott]

I wish I had a better memory.

For some reason, I was remembering/thinking that my CX-7 REQUIRED a 93-Octane fuel. I forgot that it was/is a 91-Octane requirement.

I was in the upper-area of Vermont last weekend and wanted to fill the tank before getting on the highway to come home. I had to pass on 5-6 gas stations that only had 91-Octane for their premium gas - THINKING that I needed 93. Eventually found a station, filled-up and hit the highway.

*sigh* - So I guess when 93 is not available, 91 is JUST as desirable, eh...?

[chillum]

ya fill up on 89 when half full of 93.. I m sure it was mentioned before..keeps you at least 91 at all times. Probaby not worth the extra time having to self serve. 80 cents: 8 gallons at 10cent/gallon savings when you fill half 89 octane fuel?

[erhayes]

I had a chance to run my CX7 this evening on an isolated long stretch of road. The idea was to test if my fuel load of 1/4 91 octane and 3/4 89 octane ( Both Chevron top tier fuel) would yield any observable difference in performance. In Automatic mode there was a slight hesitation just after each 2 to 3 and 3 to 4 and 4 to 5 shift that is not present with a full load of 91 octane. This was letting the AT shift rpms at about 3500 using a steady throttle setting. I also noticed a slight surging under at medium cruising (75 mph) which to me suggests that the engines ignition timing was being adjusted to compensate to lower octane fuel. I did not try any heavy runs since there was a degradation in smoothness with less than 91 octane. I suspect that WOT runs probably cause a very real increase in the AFR (richness) and retarded timing to try to offset the lower fuel grade. My conclusion which is somewhat subjective (no real time dynomometer runs while plotting load, AFR & timing) is that one should use 91 or higher except when not availiable. 90 octane may be OK based on the fact that CX7s are sold in AK ( 90 octane highest avail) but, their vehicles don't experience our summer temperatures. So, for my CX7 it is 91 or higher always. To save some $$ use chillum sugestion of 1/2 93 & 1/2 89. Ed

[CajunRacer]

My understanding goes back to the days of leaded fuel vs. unleaded fuel and has to do with the way the engine is lubricated and it is not a simple matter of programming although that plays a part as well. Cars that were designed to burn a higher octane fuel have a different style of piston ring that brings more oil onto the cylinder wall since it is burning at a higher temperature. As for the question of can you make your 07 run off of regular gas the answer is yes, but you would have to find a competent mechanic who knows what he or she is doing, change the piston rings, oil pump (maybe), and fuel/air map to make it run right. By the time you are done with all of that you probably could have spent the same amount of money over a period of 5 years of premium gas vs. regular! If someone takes the challenges...let us know how it works out. They take leaded cars and make them unleaded all the time...just a matter of time and money.

[Nash04]

Well! for the last 10,000 miles I've been running 87 octane in my 07 and haven't seen any problems with so. The performance is the same as is also the poor gas mileage. My friend has been running 87 since she had the car and now has over 16,000 miles and have not had any problems with her car so basically it's up to the driver to decide what to do. USA Today also had an article about this issue and their results were that you can use 87 octane without any problems.

[wannabe]

just to throw things off a bit, i have an 08 cx-7. when we took delivery it had 87 octane in it from the dealer. we ran through that tank, and the next three tanks have all been 93. as soon as we put the 93 in, it seemed much more responsive and the shifting DID improve. it was a little clunky initially, but once the 93 was in, it is now smooth as glass.

i'm not sure if maybe the changes for the 08 dial down the performance a bit more than the 07 or if its just the first tank jitters...but we definetly noticed a difference.

[Rick's CX-7]

Well! for the last 10,000 miles I've been running 87 octane in my 07 and haven't seen any problems with so. The performance is the same as is also the poor gas mileage. My friend has been running 87 since she had the car and now has over 16,000 miles and have not had any problems with her car so basically it's up to the driver to decide what to do. USA Today also had an article about this issue and their results were that you can use 87 octane without any problems.

Thank you for reporting this Nash! It confirms my beliefs that under normal to moderate driving, the CX-7 will do ok with 87 or 89 octane gas. For max performance though, 93 should be used, especially in the summer months.

Also, with crude oil at $130/barrel, I suspect more and more people here will be "tempted" to try 89 and even 87 octane gas.

Rick

[AWmustang]

The problem is, you never know when you are going to need to gun it.

I don't want the computer going into limp mode just as I'm trying to dart through traffic.

But to each his own. The difference between 87 and 93 octane is 18-20 cents. It was 18-20 cents when gas was $1.50 and it's still 18-20 cents now that gas is $4.00. That means the premium for premium went from 13.3% down to 5%. And with the 6% rebate i get from my credit card on gas purchases, it's like I'm paying for regular. (Yes I realize I'd still get the 6% on regular.)

[techspeak]

regular will work fine, boost will drop off a little earlier, the ECU will never let anything BAD happen, and it doesnt fall into 'limp mode'. Limp mode is an emergency running condition in the absence of key sensors or unresponsive solenoids/outputs. Using regular gas on ANY MY CX-7 will simply trigger the regular fuel maps from the ECU. If you wanna be super sure about your MY's compatability, just get the latest ECU flash.

[chillum]

techspeak,
it sounds like you have some knowledge on this. I guess the biggest fear is that any potential damage would not be covered by Mazda if they realize you are usig regular gas which would suck. Im sure they are wise to people trying this. In Miami the difference between regular and super is about 30cents. Not to mention I am getting only 14 miles/gallon consistently with very 'normal' city driving 90% of the time. That just seems brutal.

I have been monitoring my fuel with a palmpilot program (pFuel) since last august and I get 14.3miles/gal, at cost of 23 cents/mile in fuel with an avg of 3.36$/gallon (prices from last august).

thats not that cheap.. Luck I have only driven about 5000 miles since then so its not a big deal, but Im curious more than anything on this regular gas thing.

[techspeak]

techspeak,
it sounds like you have some knowledge on this. I guess the biggest fear is that any potential damage would not be covered by Mazda if they realize you are usig regular gas which would suck.

well the dealer can't, by law, deny a warranty claim based on the grade of fuel you use. I notice these dealers like to TRY and deny a lot of claims over BS, but thats just your classical dealership dishonesty. It is advised in the 07 manual as an 'emergency measure', and even fully advised for the 08. Regular fuel in this engine can't cause a warranty claim, and if it did, you were simply operating on the advice of the manual in an 'emergency situation'. Trust me, you can fill up with regular and floor the car all day long and you won't do any damage. The ECU simply will not allow it, and to it's credit, its very fast and well programmed!

On the flipside, anecdotally, some people have gotten better fuel mileage with regular (omg)... a handful of unrelated people, and they report flawless performance as well.

[PMena]

ur wrong, they had to change cats n stuff 2 run on reg for 08, along with programming for it, the emergancy mode for 07s is only temp, as sated in ur manual, if u run ur car on reg for to long it will reduce the life of ur engine severly for 07 cx7s. 08s are fine on reg.

do not run reg on 07s, u wont notice it now b/c it will take time, but ur damaging the engine, no matter how good it feels, u cant see the damage ur doing inside

[techspeak]

ur wrong, they had to change cats n stuff 2 run on reg for 08, along with programming for it, the emergancy mode for 07s is only temp, as sated in ur manual, if u run ur car on reg for to long it will reduce the life of ur engine severly for 07 cx7s. 08s are fine on reg.

do not run reg on 07s, u wont notice it now b/c it will take time, but ur damaging the engine, no matter how good it feels, u cant see the damage ur doing inside

I'm wrong? your whole post is bs bro, sorry to tell you.

the catalyst is UNAFFECTED BY ANY GAS YOU CHOOSE.

Care to specify the long term damage you speak of? I'm dying to hear this one!!

[Shaz]

I'm joining this post parade and comment on something. For the first time since I bought my CX7 last Dec. 28, 2006, I fed the car with 9 gals of 87 regular gas. Half of the tank still has the Premium gas from the last fill-up. The reason being is that Premium gas costs $4.26/gal in Chicagoland.

I dont know what it is but I felt that the car is more responsive out the line plus it seems that I am achieving better mpg as evidenced by the numbers I'm having. I used to only get around 115-130 miles when I reach half but now I'm seeing 150-165 miles on half. My driving habits, route and other factors on my daily drive didn't change.

Well, of course, I am thrilled with this. I will try midgrade fuel on my next fill-up and we shall see if my mpg will improve. I'm not planning to use regular or midgrade for a long time since if there is really a potential future problem associated with the use of fuel that is not recommended, i don't want to regret it. I will go back to using Premium again and probably will occasionally use regular and midgrade.

[SuperStretch18]

I'm wrong? your whole post is bs bro, sorry to tell you.

the catalyst is UNAFFECTED BY ANY GAS YOU CHOOSE.

Care to specify the long term damage you speak of? I'm dying to hear this one!!

Dude, I've called MNAO on this specific topic. Their answer was that you are OK running regular in a 2008, but there were changes that were made starting that year. In a 2007, "you can cause long term damage" (their words, not mine).

If you are interested in specifically how, it has to do with pre-ignition. Because lower octane fuel burns at higher temps, the cylinders on high compression or forced induction engines (we have both) can heat to the point that gasoline combusts without a spark. This is a problem when a cylinder fires on the upstroke or when some of the valves are open. Yes, modern ecu's can detect knock and make adjustments accordingly, but if the tune isn't aggressive enough, you are still going to encounter some knocking. And no, your ear is not 100% accurate to detect knocking. And no, your engine will not blow up as soon as you put a tank of regular in, but I question what the condition of the internals will be after 100k miles on regular.

Regarding the cat:
http://media.ford.com/mazda/article_display.cfm?article_id=26425&CFID=19255984&CFTOKEN=aa4e30da2cf98f38-C3918E09-1185-6933-5DAE9EA3B6C595EB


New catalyst and engine programming mean that premium fuel is now recommended, rather than required.

In the end though, do whatever you want. It's your car and if it is working for you, then go for it. And please share your experience! Just don't make assumptions like "just run the latest flash" or "Mazda can't kill your warranty because of fuel". A manufacturer can deny any warranty claim if the proper maintenance wasn't followed, which includes using the required fuel type (again, for the 07). If you have any other sources you can site regarding the law you mentioned, then please share. Just don't post Magnusson Moss, because that has nothing to do with this.

In any case, good luck to everyone. I have a 2007 though, so I won't even be attempting regular... (friday)

[Shaz]

Thanks man. That is enlightening. Well, I did put a half tank of regular recently (see my post above yours) for 2 reasons...1. It costs $4.26/gal for premium here in IL...2. I was curious as to how my car will respond in its first taste of regular fuel.

I am not planning to jeopardize my car's performance as well as its overall health so i will have to suck it up paying over $4/gal at the pumps. I will keep zoom-zooming. I love my ride

[PMena]

thnx



I'm wrong? your whole post is bs bro, sorry to tell you.

the catalyst is UNAFFECTED BY ANY GAS YOU CHOOSE.

Care to specify the long term damage you speak of? I'm dying to hear this one!!


Dude, I've called MNAO on this specific topic. Their answer was that you are OK running regular in a 2008, but there were changes that were made starting that year. In a 2007, "you can cause long term damage" (their words, not mine).

If you are interested in specifically how, it has to do with pre-ignition. Because lower octane fuel burns at higher temps, the cylinders on high compression or forced induction engines (we have both) can heat to the point that gasoline combusts without a spark. This is a problem when a cylinder fires on the upstroke or when some of the valves are open. Yes, modern ecu's can detect knock and make adjustments accordingly, but if the tune isn't aggressive enough, you are still going to encounter some knocking. And no, your ear is not 100% accurate to detect knocking. And no, your engine will not blow up as soon as you put a tank of regular in, but I question what the condition of the internals will be after 100k miles on regular.

Regarding the cat:
http://media.ford.com/mazda/article_display.cfm?article_id=26425&CFID=19255984&CFTOKEN=aa4e30da2cf98f38-C3918E09-1185-6933-5DAE9EA3B6C595EB



In the end though, do whatever you want. It's your car and if it is working for you, then go for it. And please share your experience! Just don't make assumptions like "just run the latest flash" or "Mazda can't kill your warranty because of fuel". A manufacturer can deny any warranty claim if the proper maintenance wasn't followed, which includes using the required fuel type (again, for the 07). If you have any other sources you can site regarding the law you mentioned, then please share. Just don't post Magnusson Moss, because that has nothing to do with this.

In any case, good luck to everyone. I have a 2007 though, so I won't even be attempting regular... (friday)

[techspeak]

that' 'rep at MNAO' is like most reps, clueless narketing agents. They parrot what they hear and what regional reps and managers tell them. Theyre just like a really big dealer with a reputation for the same attitude and screwing the North American Mazda market up. Yes, Mazda developed a new catalyst called "single nano technology". It is simply a method of manufacturing durable high efficiency catalysts with less precious metals. It's being introduced on all Mazda models. A catalyst will not be different between regular or premium.

It comes down to the old "consumer trust" issue. Some consumeristic people have a need to trust percieved "officials", ie doctors, service writers, office monkeys, well beyond reason. They will not think about it, for they need not think about it. A figure they percieve as authoratative has said something, and thats about as far deep as you should bother looking, right? (but thats another sociopathic phenomenon, for another day)

Look, I fully understand preignition and detonation, but what I don't understand is why people are worried about it, when the ECU will not, and can not allow knocking or detonation to occur If the ECU could not stop knocking or detonation by adjusting, then you would be bucking down the road all day as the ECU shuts the throttle. NOT GOING TO HAPPEN, because BOTH 07 and 08 CAN EASILY, WITHOUT DANGER, RUN ON REGULAR GAS. I'm not going to say that anymore, if you can;t understand that, you deserve to pay the high price of premium. The ECU (on data loggers) show that it responds to knock after ONE knock condition. To understand how fast this can happen, lets do some calculations:

4000rpm = 2000power strokes.
2000 power strokes * 4 cyl
=8000 overall engine power strokes per min
/ 60 = 133 power strokes per second

If the ECU responds to ONE knock condition from ONE cylinder at 4000rpm, before the next knock cycle could occur means the ECU has seen, and corrected for knock in... 0.0075 seconds!! THAT IS FAST! The people who say regular will ruin or even injure the 2.3L DISI are the same people who havent a clue of the hardware they are working with. I guess it's only karmic justice that you pay the premium for premium? lol

[SuperStretch18]

I know the talking points, but the fact is that knock has to occur before it can be detected...

Whatever though; we'll just have to agree to disagree. Like I said, I'm not really concerned with what others do with their cars. The extra four dollars I spend once a week buys me peace of mind. I'll happily spend it; karma or not. [insert.whiteflag--->here]

[erhayes]

I have had my engine knock loudly when I was in third gear and decided to accelerate. The AT did not downshift under the medium throttle and the knocking started. I let off imediately. I will not try 87 or 89 octane again. This on a top tier fuel. The ECM may be fool proof, is not idiot proof in my opinion.

[Zoom49]

I also have had my CX-7 knock loudly on several occations. I have used onlypremimun fuel (91 here in Calif) I have taken it to the dealer twice for this issue and they say that there is nothing they can do. I have tried several different brands of fuel to no avail. Seems to happen more often in the summer but does not seem to be related to heat soak as it has happened on highway during an extended drive cycle.

[Rick's CX-7]

regular will work fine, boost will drop off a little earlier, the ECU will never let anything BAD happen, and it doesnt fall into 'limp mode'. Limp mode is an emergency running condition in the absence of key sensors or unresponsive solenoids/outputs. Using regular gas on ANY MY CX-7 will simply trigger the regular fuel maps from the ECU. If you wanna be super sure about your MY's compatability, just get the latest ECU flash.

Likely the smartest, most informed post in this whole thread!
Thanks for your input.

Rick

[Rick's CX-7]

Well, I totally agree with techspeaks comments. The thing most people here need to understand is the total control the ECM has on these cars. The minute the computer detects something "weird" it shuts the throttle partially or completely; not to mention timing, fuel, etc.

The best way to confirm this is to drive on ice. Floor the car from a standing still on ice and the throttle closes instantly. You can hit the gas all you want, but you won't go past ~2k RPMs. That is control!

I also agree the cats have nothing to do with fuel. Too lean or too rich a mixture could burn the cats, but octane difference doesn't make a difference. Heavy oil burning can also kill a cat, likely it's biggest enemy.

Rick

[SuperStretch18]

One of the changes that the ECU is going to make if it sees detonation is to dump more fuel into the mix to cool the combustion chamber. In doing so, the chances of unburnt fuel making it to the cat and burning there increases. If you know that you are going to be running ultra rich more frequently, then you can change the cat to one that would stand-up better to the heat.

I agree that melting your cats is not catostrophic engine failure, but it does seem likely that Mazda was trying to avoid the issue. Seems pretty logical to me...

[AWmustang]

Gas is expensive. Premium gas is more expensive. Mazda does not make gas.

What motivation would Mazda have for requiring (2007) or even recommending (2008) premium gas?

The only things I can think of is that the loss of sales was outweighed by improved longevity of the various engine components or the increased power the engine makes on premium.

Well I want that power available to me so I'm going to use the premium. Until I see some dyno runs that prove to me the car makes just as much power on regular, I won't believe that there's no difference.

[wannabe]

Gas is expensive. Premium gas is more expensive. Mazda does not make gas.

What motivation would Mazda have for requiring (2007) or even recommending (2008) premium gas?

The only things I can think of is that the loss of sales was outweighed by improved longevity of the various engine components or the increased power the engine makes on premium.

Well I want that power available to me so I'm going to use the premium. Until I see some dyno runs that prove to me the car makes just as much power on regular, I won't believe that there's no difference.


i agree.

[marciano]

i use premium in mine...i knew what i was getting before i bought it...alot of the other suv/crossovers may run on rugular, but have no persoanlity or styling..ala the rav4...or get sucky mpg like the explorer. i love mine and i think getting 23-25 mpg out of mine is well worth the extra 5 bucks at the pump for the performance and mpg