My 2009 mazda cx7 recommends premium grade gas.

I have been using mid grade for about 5 years with no issues.

I get the advertised gas mileage. 20/28 city highway.

Is my car retarding the timing by that?

I read where that can causing knocking.

Wondering if regular gas would work.

The price used to be only about 30 cents more to upgrade to midgrade.

That is no longer the case.
Thanks,
Andy

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AK <scientist77017@gmail.com> wrote:

My 2009 mazda cx7 recommends premium grade gas.

I have been using mid grade for about 5 years with no issues.

I get the advertised gas mileage. 20/28 city highway.

Is my car retarding the timing by that?

Put it on a scanner and see. If you're not driving aggressively, it might
not be. If you're driving aggressively, it might be.

I read where that can causing knocking.

No, the computer system will retard the timing to prevent that from happening. It's not like the engines of the seventies where you could damage them by
using too low octane fuel. Now all you lose is performance when the system pulls the timing back.

Wondering if regular gas would work.

Maybe, try it. It won't hurt anything. It might not accelerate so well,
but that might not bother you. Or maybe it will. Try it.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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On Tuesday, September 6, 2022 at 11:54:44 AM UTC-5, Scott Dorsey wrote:

AK <scienti...@gmail.com> wrote:

My 2009 mazda cx7 recommends premium grade gas.

I have been using mid grade for about 5 years with no issues.

I get the advertised gas mileage. 20/28 city highway.

Is my car retarding the timing by that?

Put it on a scanner and see. If you're not driving aggressively, it might
not be. If you're driving aggressively, it might be.

I read where that can causing knocking.

No, the computer system will retard the timing to prevent that from happening.
It's not like the engines of the seventies where you could damage them by using too low octane fuel. Now all you lose is performance when the system pulls the timing back.

Wondering if regular gas would work.

Maybe, try it. It won't hurt anything. It might not accelerate so well,
but that might not bother you. Or maybe it will. Try it.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

I will try regular gas at my next fill up.

See if there is any performance or mileage changes.'

Andy

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AK said:

I will try regular gas at my next fill up.
See if there is any performance or mileage changes.

A lot depends on the vehicle, the altitude, the air pressure, the engine,
the way you drive, the load, etc., but you won't notice anything different
most likely.

For gas mileage you won't notice a difference because your volumetric error outweighs any theoretical differences between retarding the timing a few degrees under heavy load.

For performance, unless you're racing, you won't likely notice the slight retardation in timing under load and, in fact, the OPTIMUM performance, I
was told long ago, is when you are at the nanodegree of timing BTC prior to knocking.

Hence it may be easily that you get better gas mileage and better
performance, but my first two statements will outweigh them all.

1. It depends on the mechanical factors, but,
2. Almost certainly, you won't notice any difference.

If you checked timing under load, you might see the difference but most
cars, I'm told, constantly change timing so you'd need to compare graphs
from different runs (which goes back to my statement that you can't measure
the difference with your equipment).

If I'm wrong, let me know as I don't mind learning from others.

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On Monday, September 5, 2022 at 4:49:35 PM UTC-4, AK wrote:

My 2009 mazda cx7 recommends premium grade gas.

I have been using mid grade for about 5 years with no issues.

I get the advertised gas mileage. 20/28 city highway.

Is my car retarding the timing by that?

I read where that can causing knocking.

Wondering if regular gas would work.

The price used to be only about 30 cents more to upgrade to midgrade.

That is no longer the case.
Thanks,
Andy

_________________

I've heard that it's better in the long run, for lawn and snow equipment, to splurge on a 1-2gallon
tank of 89 or 93 octane gas, because I was told it had a lower amount of ethanol or mtbe in it -
additives that can damage mowers, leaf blowers, and snow machines.

Any validity to this claim?

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On Monday, September 5, 2022 at 4:49:35 PM UTC-4, AK wrote:

My 2009 mazda cx7 recommends premium grade gas.

I have been using mid grade for about 5 years with no issues.

I get the advertised gas mileage. 20/28 city highway.

Is my car retarding the timing by that?

I read where that can causing knocking.

Wondering if regular gas would work.

The price used to be only about 30 cents more to upgrade to midgrade.

That is no longer the case.
Thanks,
Andy

_________________

I've heard that it's better in the long run, for lawn and snow equipment, to splurge on a 1-2gallon tank of 89 or 93 octane gas, because I was told it had a lower amount of ethanol or mtbe in it - additives that can damage mowers and snow throwers.

Any validity to this claim?

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On Monday, September 12, 2022 at 6:41:05 PM UTC-4, Scott Dorsey wrote:

Chris K-Man (Zickcermacity) <thekma...@gmail.com> wrote:

I've heard that it's better in the long run, for lawn and snow equipment, to splurge on a 1-2gallon tank of 89 or 93 octane gas, because I was told it had a lower amount of ethanol or mtbe in it - additives that can damage mowers and snow throwers.

Any validity to this claim?

MTBE and ethanol are added to gasoline to increase octane.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres

__________

About two seasons ago, my local small engine repair place told me to
buy higher octane gas because it contained less of those additives, which he said harms the engines in lawnmowers and snow blowers.

If I wanted to increase octane, I would simply buy 93 all the time!

duhhh..

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Chris K-Man (Zickcermacity) <thekmanrocks@gmail.com> wrote:

I've heard that it's better in the long run, for lawn and snow equipment, to splurge on a 1-2gallon tank of 89 or 93 octane gas, because I was told it had a lower amount of ethanol or mtbe in it - additives that can damage mowers and snow throwers.

Any validity to this claim?

MTBE and ethanol are added to gasoline to increase octane.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

--- SoupGate-Win32 v1.05
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On Monday, September 12, 2022 at 1:15:52 PM UTC-5, harry hornsley wrote:

AK said:

I will try regular gas at my next fill up.
See if there is any performance or mileage changes.

A lot depends on the vehicle, the altitude, the air pressure, the engine,
the way you drive, the load, etc., but you won't notice anything different most likely.

For gas mileage you won't notice a difference because your volumetric error outweighs any theoretical differences between retarding the timing a few degrees under heavy load.

For performance, unless you're racing, you won't likely notice the slight retardation in timing under load and, in fact, the OPTIMUM performance, I
was told long ago, is when you are at the nanodegree of timing BTC prior to knocking.

Hence it may be easily that you get better gas mileage and better performance, but my first two statements will outweigh them all.

1. It depends on the mechanical factors, but,
2. Almost certainly, you won't notice any difference.

If you checked timing under load, you might see the difference but most
cars, I'm told, constantly change timing so you'd need to compare graphs
from different runs (which goes back to my statement that you can't measure the difference with your equipment).

If I'm wrong, let me know as I don't mind learning from others.

I probably won't see any performance change.

But my wallet will.

Getting reg gas will save me $5.40 per fill up. :-)

Andy

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On 9/12/2022 4:16 PM, Chris K-Man (Zickcermacity) wrote:

On Monday, September 5, 2022 at 4:49:35 PM UTC-4, AK wrote:

My 2009 mazda cx7 recommends premium grade gas.

I have been using mid grade for about 5 years with no issues.

I get the advertised gas mileage. 20/28 city highway.

Is my car retarding the timing by that?

I read where that can causing knocking.

Wondering if regular gas would work.

The price used to be only about 30 cents more to upgrade to midgrade.

That is no longer the case.
Thanks,
Andy

_________________

I've heard that it's better in the long run, for lawn and snow equipment, to splurge on a 1-2gallon tank of 89 or 93 octane gas, because I was told it had a lower amount of ethanol or mtbe in it - additives that can damage mowers and snow throwers.

Any validity to this claim?

I don't know about where you live , but here we can get non-ethanol
premium . Useta be able to get non-eth regular too but they shut that
station down because they wouldn't lease new pumps . I burn that premium
in my bikes , and a 50/50 mix in my Stihl engine tools - until they cut
off my supply of N-E regular , now they too will get premium when my
supply of 50/50 is gone.
I don't know yet what the new motor in the truck wants but I'm hoping
it'll burn 87 octane - with a 9.7:1 c/r and other performance mods it
might want mid-grade . It's old enough (1986) that it doesn't have
computerized controls . Fortunately it's not destined to be a daily
driver , it's my toy now . Can you say "sleeper" ?
--
Snag
"You can lad a dummy to facts
but you can't make him think."

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