Premium or Regular Gas?

jimdogs

Member
Does anyone know if it really makes that much of a difference if you use 87, 89 or 91 Octane Gasoline in the new CX-7? Will it cause damage or just performance problems? thanks jim
 
jimdogs said:
Does anyone know if it really makes that much of a difference if you use 87, 89 or 91 Octane Gasoline in the new CX-7? Will it cause damage or just performance problems? thanks jim
I've used one tank of mid-grade (89 octane) and I noticed that the insides of those bright exhaust pipes are sooty looking, in spite of my rather aggressive driving style. Won't do that again!

I'm afraid to use 87 octane for fear of detonation (pinging, spark knocking, or whatever name you know it by).
 
jimdogs said:
Does anyone know if it really makes that much of a difference if you use 87, 89 or 91 Octane Gasoline in the new CX-7? Will it cause damage or just performance problems? thanks jim

Somewhere Mazda has said that using 87 will force the engine into "emergency mode." I'd say stick with the recommended 91, especially if you bought the car and don't want to find out what "emergency mode" is.
 
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The manual specifies 91, so I've only put in premium. The inside of my tailpipes look sooty too, though. It might be because of the chemicals burning off the engine or something? I dunno...
 
it's the same basic engine as the mazdaspeed 6, and that car REQUIRES premium, so put premium in there!
 
Cheap!

jimdogs said:
Does anyone know if it really makes that much of a difference if you use 87, 89 or 91 Octane Gasoline in the new CX-7? Will it cause damage or just performance problems? thanks jim

This engine has a big compression ratio. Premium fuel is part of the design.

If you can't afford premium, buy a Mazda 3 instead.

No such thing as a free lunch!
 
"Emergency mode" happens if the engine senses less than 91 octane...cuts boost by 30%. That's what I've heard.
 
Premium fuel is for the turbo engine......if you use regular fuel you reduce your HP by s*** loads.....

BTW to run premium fuel based on 20000 km per year it costs you only 60 cents a day (cdn bux eh)
 
My Mazda

I have an RX 8 and granted it's a rotary engine but I have to say stick with the premium. When I put midgrade in it it really acts up...loses power, idles rough etc. With a turbo I bet it really needs the premium. I know gas prices stink and I tried midgrade for awhile and nothing but problems....I took it in and they found no issues and mentioned it's probably the gas...I did not have the heart to say I have been using mid grade off and on. I am considering a CX7 for my next vehicle so this topic interested me. Enjoy the CX7 folks!!! It was a blast to drive!
 
If you wanna see what lower octane gasoline does to this engine, just do a search in the Mazdaspeed6 board for "power loss." Not good. I've had it happen to me twice in my Speed6, even with 93 octane. Word is there's a software upgrade for it now that will fix it so that the knock sensor isn't so overzealous.

What happened is something along the lines of the engine protecting itself as soon as it detects even a hint of detonation, and it dramatically lowers the boost (actually, I believe it cuts the throttle by a significant amount).

Trust me, you don't want to try anything under 91, and I'd highly suggest you use 93 if you can get it.

As for the CX-7, I'm trying to slowly convince my wife that when we're ready to turn in her Forester in another 20-30K miles, she needs to get one of these. :)

The difficulty is going to be convincing her that it will be as reliable as the only-scheduled-maintenance-needed Subaru (almost 70K miles and nothing other than scheduled maintenance, knock on wood). My Speed6 has already been in the shop twice for different things in 4500 miles.
 
stillflat4 said:
Trust me, you don't want to try anything under 91, and I'd highly suggest you use 93 if you can get it.

So, you're saying given a choice between 91 and 93, put in 93?
 
080669 said:
So, you're saying given a choice between 91 and 93, put in 93?

I would. I am sure Mazda is releasing the CX-7 with the update that the new MS6 firmware provides. Mazda recommends 91 or above with the MS6, but most of us needed to use 93 (if we're in an area of the country that can get it) to avoid the oversensitive knock sensor from being tripped. I have just made it a matter of fact to get 93, and I think if you asked over on the MS6 forum, most of the people over there do the same.

I doubt you will need to be that careful with the CX-7, since hopefully Mazda learned a little about American gasoline. There's some site out there that lists the highest quality gasolines based upon quality control and cleaning power. I forget where it is, maybe someone here knows where it is. I looked at the list and the only distributor on the list here in NY was Shell, so I started using that exclusively (and got a shell gas card that I use JUST for gasoline -- $30 in rebates so far, and it takes the hit out of the extra I spend on premium fuel). I know Chevron is on the list too, but I forget what other companies are on there.

Sorry to go on... I think the point is that if you use quality fuels, I think you'll be all right with 91, but my earlier point was that you do NOT want to tempt "emergency mode" by using anything less. If it was my car, I would use 93. I wouldn't bother with 94 even if I could get it here (Sunoco stopped selling it here a few years ago).

I know some people claim that all gasoline comes from the same tankers, no matter the brand. I don't think that's true, and no one has shown me otherwise.

That said, I'm still open to convincing. :)
 
hmm *bump*

I want to be using "top tier" gasoline but I don't believe any of those retailers are in my area :'(

In Rochester, NY I am able to go to:
Sunoco
Citgo
Exxon/Mobil (I refuse to go there, filthy bastards www.exxposeexxon.org)
Hess
BJs
Delta Sonic (I think it's sorta a local chain)
... pretty much just local places other than that.

There might be a "kwikfill" but I'm not sure. I know on the New York State Thruway there is ONLY Exxon or Sunoco, and pretty much going in one direction (east or west, I can't remember right now) you can only get Sunoco, in the other only Exxon.

:( I want to be putting clean gas in my car, what to do?
 
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