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Folks just keep on posting...

Its right up there with, "should I use synthetic or dyno oil," "what tint to get," and "what color HID bulb should I use?" Oh, and "will these rims and/or tires fit my car?"
:wink2:
LOL. :nerd:

1. Definitely use oil!
2. Definitely get tint if you want to!
3. Get the best HID bubb for you!
4. Yes, those 25s will fit fine! Go ahead and send him your money!
 

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The best type of 87 octane to use, IMHO, is Chevron w/Techron. I have noticed a significant difference in performance and fuel economy in my 2015 Mazda 3 w/ the 2.0 liter engine since they've switched to the new additive formula. Before, I had been using Shell's 87 octane.
 

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Any of the "Top Tier" gas is fine. The scheme used to be that only the premium grades got the full additive package, but the "Top Tier" designation changed that. All the fuel comes out of the same rack and refineries; the only difference is in the additive package -- which is put in at the terminal.
 

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Any real reason for using higher than 87 octane?
I always felt like my car ran better in warm weather on premium. That's a seat-of-the-pants opinion...and a lot of people will say I'm full of s***. However, it stands to reason that in hotter weather, the ecm will pull less timing if I'm running a more knock resistant fuel than 87. More timing...better performance. Is it worth the price difference? Probably not, unless you want to wring the last little ounce of go out of your car.

Anyway, try running some premium and see for yourself...or, don't.
 

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I believe running premium results in less crankcase oil fuel dilution in a car that has short-run in-city useage patterns. That is 'cuz when a direct injected engine has to quell preignition it either trims back timing or enrichens the mixture by adding fuel. When it does the latter, excess fuel makes its way to the crankcase due to typically low-tension piston rings... used to lessen friction/improve fuel economy. With premium it lessens the fuel enrichment tendencies/needs.
 

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Any of the "Top Tier" gas is fine. The scheme used to be that only the premium grades got the full additive package, but the "Top Tier" designation changed that. All the fuel comes out of the same rack and refineries; the only difference is in the additive package -- which is put in at the terminal.
Correct. Regardless of which octane you use, make sure it is a "TopTier" outlet.

I always felt like my car ran better in warm weather on premium. That's a seat-of-the-pants opinion...and a lot of people will say I'm full of s***. However, it stands to reason that in hotter weather, the ecm will pull less timing if I'm running a more knock resistant fuel than 87. More timing...better performance. Is it worth the price difference? Probably not, unless you want to wring the last little ounce of go out of your car.

Anyway, try running some premium and see for yourself...or, don't.
Motors with a Turbo(s) are more subject to fuel dilution. Technically, premium should result in slightly more power and a slight increase in mpg. For example the 3.5 Twin Turbo in my truck runs fine on 87 (recommended) but Ford recommends premium when towing. You will never get better mpg using premium where it will make it worth it $ wise. If you want to save money at the pump use 87, never anything less. If it makes you feel better and you believe your car runs better on premium, the extra money doesn't matter, use premium.

Listen to your engine. If you step on it and you hear it pinging while using 87, switch gas stations. If it continues, use a higher octane.
 

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The Skyactive 2.5T (2018) has different ratings according to Mazda '250 HP with 93 octane fuel. 227 HP with 87 octane fuel.'

How do you think it makes this adjustment; knock sensor? I have 92 octane available and guess I will get some boost. Any insight on this?
 

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The Skyactive 2.5T (2018) has different ratings according to Mazda '250 HP with 93 octane fuel. 227 HP with 87 octane fuel.'

How do you think it makes this adjustment; knock sensor? I have 92 octane available and guess I will get some boost. Any insight on this?
Having this subject debated at great length on the F150Forums, it is believed and proven that the higher octane with a torbo'd motor does increase HP. Mazda is telling you the same thing.... you want 23 more HP, run 93, if you're good with 227 run 87. I would assume that as you lower octane using 93 as your base you will incrementally reduce HP. Running 92 oct. will deliver 245HP. ?
 

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Listen to your engine. If you step on it and you hear it pinging while using 87, switch gas stations. If it continues, use a higher octane.
With modern knock sensor technology, I'm thinking the ECM is retarding timing long before you might hear anything. We are talking 13:1 compression.
 

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... it is believed and proven that the higher octane with a torbo'd motor does increase HP. Mazda is telling you the same thing.... you want 23 more HP, run 93, if you're good with 227 run 87. I would assume that as you lower octane using 93 as your base you will incrementally reduce HP. Running 92 oct. will deliver 245HP. ?
Mazda says the torque from the turbo is unchanged by octane; it is 310 pf regardless of octane.
High octane does allow more ignition advance which produces 25 more hp.
 

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Mazda says the torque from the turbo is unchanged by octane; it is 310 pf regardless of octane.
High octane does allow more ignition advance which produces 25 more hp.

And that is a bunch of feldercarb; HP is a function of torque, basically torque is measured at an RPM and then HP is calculated from that.



HP = (Torque x RPM) ÷ 5252
 

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Well, not really, because the usual situation is that peak torque is fairly low in the RPM band comparatively. With dynamic boost control it is not uncommon at all for the engine to be unable to run more advance with higher-octane fuel at that particular point in the torque curve, so there's no difference.

However you do get more advance and more torque at higher RPM, thus more horsepower. But that's not the point of maximum torque.
 

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Listen to your engine. If you step on it and you hear it pinging while using 87, switch gas stations. If it continues, use a higher octane.
With modern knock sensor technology, I'm thinking the ECM is retarding timing long before you might hear anything. We are talking 13:1 compression.
Yes, your sensors will retard the timing with 87 and you should not hear it ping.
I guess my point about if you're hearing it ping is your gas station is pumping gas that is quite inferior = change stations


Mazda says the torque from the turbo is unchanged by octane; it is 310 pf regardless of octane.
High octane does allow more ignition advance which produces 25 more hp.
Correct

87 is what's recommended
It is the MINIMUM recommendation


peak torque is fairly low in the RPM band comparatively. With dynamic boost control it is not uncommon at all for the engine to be unable to run more advance with higher-octane fuel at that particular point in the torque curve, so there's no difference.

However you do get more advance and more torque at higher RPM, thus more horsepower. But that's not the point of maximum torque.
Yup.

HP is how fast you hit the wall. Torque is how far you go through the wall. :grin2:
 

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Well, not really, because the usual situation is that peak torque is fairly low in the RPM band comparatively. With dynamic boost control it is not uncommon at all for the engine to be unable to run more advance with higher-octane fuel at that particular point in the torque curve, so there's no difference.
However you do get more advance and more torque at higher RPM, thus more horsepower. But that's not the point of maximum torque.
I'll compromise and say we are both correct; peak torque may not have increased, but the torque at the maximum HP would have.
 
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