Regular Gas for 2008 CX7

[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...a2cf98f38-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...a2cf98f38-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)