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The key to the fuel is using a top tier fuel. Google it. That doesn't mean top tier OCTANE. Fuels that are certified TOP TIER have detergents in them that keep the engine clean and free from carbon build up, which direct injection engines are prone to.

Your best defense, to the above, is top tier fuel and regular synthetic oil changes...
Yes, I remember researching this many years ago. I narrowed down here in Canada to only going to Costco and shell as the ones with top tier gas.


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Yes, I remember researching this many years ago. I narrowed down here in Canada to only going to Costco and shell as the ones with top tier gas.


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IMO: For this well designed GDI/ turbo engine use of a top tier gasoline product to reduce combustion chamber carbon, and reduce injector deposits is indicated. I use 93 octane not just for the added HP/TQ fun factor, but to help combat any CC predetonation given the rather high 10.5- 1 compression ratio ( for a turbo) and given the recycled exhaust via the EGR into the CC. In addition I strongly support the use of high quality synthetic oils, with the API SP and ILSAC GF6 certifications, helping to reduce intake valve deposits, and frequent oil change intervals. this engine makes a ton of heat It is tough on oil. I’ll also note in the owners manual in the turbo model section, it recommends after extended freeway type driving, towing, or extended hills to allow the motor to idle for 30 seconds before turning the engine off. LOVE this car!
 
I did some testing using exclusive Exxon gas. 93 Vs 87 and I have to say I can't tell the difference but I drive car very gently. I did some research and some say that car needs to be pushed to around 5000RPM to get a feel in HP difference. My car never seen 3500RPM so I put premium every other tank just to feel better I guess.

On another note (Can Anybody confirm it please) - CX50 Turbo is air cooled only???? Most turbos these days are both liquid and air cooled but I found info that 2021/2022 Mazda CX5 turbos are exclusively air cooled!!!!
If that's the case, we better keep these things running for a minute or two before turning the engines off.....
Correct, the manual says to give the engine or rather, turbocharger, a quick break after spirited driving. And there’s also torque charts that show sustained torque past 4000rpm which should give a feeling of sustained power rather than a very sharp drop-off with 87. Otherwise, supposedly, there is little difference. Anecdotally and maybe placebo effect but I do find the car drives nicer overall with premium fuel. I just chase those deals when premium sells for the price of regular.

I have tuned and datalogged many cars. The most consistent gas I have seen is Costco. The most inconsistent…Shell.
Gas quality varies significantly by region. There's a fellow who did an entire YouTube series showcasing the different fuels we have here in the lower mainland, BC. Costco was inconsistent and kind of a joke to him. Previous Shell was inconsistent. Chevron I believe was fine. But the best fuel he tested was Chevron 92 from across the border, something that is different from the 91 and 94 product we have up here. He says the new Shell we have 91/93 (no longer ethanol-free) was also very good.

Yes, I remember researching this many years ago. I narrowed down here in Canada to only going to Costco and shell as the ones with top tier gas.
You may be thinking of ethanol-free versus Top Tier gas? There's a few Top Tier gas options we have up here in Canada, at least more than just Costco and Shell, but very little ethanol-free, depending on where you live. There is qualification criteria to be "Top Tier" so it may hold value for some independent brands as you don't know the quality/amount of detergents in them. Keep in mind though that brands pay licensing fees to be Top Tier and that Esso recently lost their Top Tier designation. Do I really believe that Synergy-branded fuels with all their marketing of being high quality fuel with high-end detergents are in the same tier as Super Save and not comparable with Shell? Very debatable. It's more likely they just didn't want to pay for the Top Tier branding anymore.

Ethanol-free (at least in the lower mainland) may be select Costco only (and the gas attendant that I asked last time had no idea). Pumps are marked "may contain up to 10% ethanol). Chevron 94 is ethanol-free. None of Shell's highest end fuels here are ethanol-free anymore.
 
Folks.. No one mentioned this directly but it's proven that if we use 87 Octane we get the 227 HP and 310 Tq but if we use 93 Octane we get 256 HP and 320 TQ so yes.... this engine there is absolutely a difference..... This is information from Mazda, not some 87 Octane vs 93 Octane forum...


Use 93 Octane!
 
Folks.. No one mentioned this directly but it's proven that if we use 87 Octane we get the 227 HP and 310 Tq but if we use 93 Octane we get 256 HP and 320 TQ so yes.... this engine there is absolutely a difference..... This is information from Mazda, not some 87 Octane vs 93 Octane forum...


Use 93 Octane!
Yes, those are the performance figures with 87 and 93 octane fuel but you need to consider when those numbers are hit.

The engine makes 250 HP at 5000 rpm. How often do you hit 5000 rpm? The engine makes up the difference between 227 and 250 HP between 4000 and 5000 rpm.

The engine hits peak torque at 2500 rpm. The main difference between 87 and 93 octane is a much sharper drop off after 4000 rpm. How often do you drive past 4000 rpm?

Because HP peaks at 4000 rpm and because torque starts to fall off sharply, the engine starts to feel real anemic past 4000 rpm on 87 octane. 93 octane provides significantly more oomph after 4000 rpm. This is really the only significant difference. The torque and HP curve is near identical up to 4000 rpm so for most drivers and city driving, there shouldn’t be much of a difference.
 
Costco in Canada sells top tier fuel, true.
Costco does not have an oil refinery, as such their fuel supply comes from various top tier suppliers.
It could be Shell, Coop, Esso, etc.
In severe cold temperatures the octane differences have very little effect on performance.
In my CX 30 turbo I found 93 octane ran smoother with a slightly better fuel economy (negated by the higher price), and if you don’t drive often or have the need to fuel up often it stays fresher. (Apparently).

Every jerrycan I own has premium regardless if it is mixed or pure, the longer shelf life theory is my reasoning.
If I am just going back and forth to work 5 days a week with an occasional trip elsewhere, I can make a tank of fuel last a month.

I run premium, but really don’t notice the performance increases at all.
No dyno, just seat of the pants.
 
Yes, those are the performance figures with 87 and 93 octane fuel but you need to consider when those numbers are hit.

The engine makes 250 HP at 5000 rpm. How often do you hit 5000 rpm? The engine makes up the difference between 227 and 250 HP between 4000 and 5000 rpm.

The engine hits peak torque at 2500 rpm. The main difference between 87 and 93 octane is a much sharper drop off after 4000 rpm. How often do you drive past 4000 rpm?

Because HP peaks at 4000 rpm and because torque starts to fall off sharply, the engine starts to feel real anemic past 4000 rpm on 87 octane. 93 octane provides significantly more oomph after 4000 rpm. This is really the only significant difference. The torque and HP curve is near identical up to 4000 rpm so for most drivers and city driving, there shouldn’t be much of a difference.

Yes it is important to know when peak numbers are reach. However, for a CX-50 where we need to to start is understanding what octane fuel actually does. It controls combustion. Let's say for example you're getting 227 HP at your stated 5k RPM. Well on 93 Octane you are now hitting 227 HP at say... 3k RPM.... You get longer strokes during combustion and the ECU adjusts the timing so you get higher HP throughout the entire rev band (as well as higher torque)

Have you ever seen a dyno chart? It's obvious what timing and other variables do to the torque and power curve. To your point each one does not hit peak until a certain RPM but from 87 to 93 the HP and TQ will always be more than the other from 1k RPm to 2k RPM to 3k RPM to 4k RPM.

I think one of your major issues is Canada mostly only has 91 octane gas at most pumps yeah? So if it's 91 The ECU may not be able to calculate the adjustments to the full 256 HP
 
Yes it is important to know when peak numbers are reach. However, for a CX-50 where we need to to start is understanding what octane fuel actually does. It controls combustion. Let's say for example you're getting 227 HP at your stated 5k RPM. Well on 93 Octane you are now hitting 227 HP at say... 3k RPM.... You get longer strokes during combustion and the ECU adjusts the timing so you get higher HP throughout the entire rev band (as well as higher torque)

Have you ever seen a dyno chart? It's obvious what timing and other variables do to the torque and power curve. To your point each one does not hit peak until a certain RPM but from 87 to 93 the HP and TQ will always be more than the other from 1k RPm to 2k RPM to 3k RPM to 4k RPM.

I think one of your major issues is Canada mostly only has 91 octane gas at most pumps yeah? So if it's 91 The ECU may not be able to calculate the adjustments to the full 256 HP
Actually most major fuel supply companies here have 3 grades. Reg 87, Mid 91 and Premium 93.
Some stations have 94 Octane in certain areas (Petro Can) Some also have 89. Husky had 5 choices on a single pump when you included diesel. Make sure your glasses are on when selecting.🤣
 
Yes it is important to know when peak numbers are reach. However, for a CX-50 where we need to to start is understanding what octane fuel actually does. It controls combustion. Let's say for example you're getting 227 HP at your stated 5k RPM. Well on 93 Octane you are now hitting 227 HP at say... 3k RPM.... You get longer strokes during combustion and the ECU adjusts the timing so you get higher HP throughout the entire rev band (as well as higher torque)

Have you ever seen a dyno chart? It's obvious what timing and other variables do to the torque and power curve. To your point each one does not hit peak until a certain RPM but from 87 to 93 the HP and TQ will always be more than the other from 1k RPm to 2k RPM to 3k RPM to 4k RPM.

I think one of your major issues is Canada mostly only has 91 octane gas at most pumps yeah? So if it's 91 The ECU may not be able to calculate the adjustments to the full 256 HP
Nah, I usually fill with 93 up here, with 94 ethanol-free also available.

I haven’t dynoed my car myself but the general 2.5T chart is available for this engine from Mazda, which I brought up in my previous post. The engine hits 227 HP at 4000rpm with both 87 as well as 93 octane. With 87, that is basically peak HP. With 93 octane, the engine achieves 250+ HP at 5000rpm. So the difference is achieved between 4000-5000 rpm, not earlier. Same with the torque curve, there is a sharp drop off past 4000rpm but identical before that.

Basically the default Mazda tune keeps both HP and TQ the same up to 4000 rpm on both 87 and 93 octane, if you trust the charts. So with everyday driving, there shouldn’t be much of a difference.
 
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