Premium gasoline for GDI?

[wolf_06]

Hi folks,

I recently bought a brand new 2018 Mazda 3 GS six speed auto with the 2.0L skyactiv GDI engine.

The owners manual recommend regular octane 87 fuel, but higher grade like 93 can be used.

This topic has probably been on here several times, but is the higher octane would benefit the the 2.0 skyactive engine? Since its a slightly higher compression engine, the manual doesnt recommend using fuel with a certain % of ethanol in it, not sure exacly how much the %, but here in Canada, gas stations sometime mention "up to 10% ethanol", only shell doesnt have any.

Should I stick with regular only or go higher grade gas to be safe. Some Mazda forums say the skyactive is design for regular gas, how true this is?

Please share your opinion on this.

Thank you!

 

[Jimzz]

If the manual says 87 then run 87.

If you are going to tow and/or haul a lot of weight then premium might help on some newer motors if it says will adjust for premium. Some cars will say 187hp on regular and 193hp on premium type thing.

 

[PimTac]

The engine will run fine on 87. I found with my SkyActiv 2.5 that it did respond better running premium which is 91 or 92 here depending. I noticed a difference going up hills and we have plenty.

There is also a train of thought that running premium will reduce fuel dilution. I don't know if that has been proven or not but my oil does not smell like it's full of fuel when I change it. I haven't had a analysis done though.

The computer will adjust the timing. If you are curious, run a tank or two and compare.

 

[Dave1027]

Try all three grades and see which one you like best. I found 89 works best in our vehicles. Much better than 87. Don't notice much difference between 89 and 91.

 

[WhizkidTN]

Originally Posted by Jimzz
If the manual says 87 then run 87.

If you are going to tow and/or haul a lot of weight then premium might help on some newer motors if it says will adjust for premium. Some cars will say 187hp on regular and 193hp on premium type thing.


FWIW:
I own a turbo Optima SX rated at 274HP/269ft-lb on 87 octane stock. The ECU will adjust if you run 93 octane and net about 10HP more. Many modern cars can do this now.

I run a full ECU tune with lots of bolt-on parts and must run 93 octane (Top Tier) fuel and just love the big boost in performance (~340HP/320ft-lb).

 

[ArtDart]

When I got my ‘17 Mazda CX-5, I used 87 E10 gas...
The oil level on dipstick kept rising.
I changed the FF @ 1500 mi & started using 91 E0 gas..
Oil level on dipstick has remained rock solid ever since, despite my ultra short tripping usage.
I only fill up once a month, so the additional cost is minimal & worth it to me.
I believe the owners manual says to use a MINIMUM of 87 octane

 

[Triple_Se7en]

Originally Posted by Dave1027
Try all three grades and see which one you like best. I found 89 works best in our vehicles. Much better than 87. Don't notice much difference between 89 and 91.


What vehicle and engine are you discussing?

 

[dave1251]

Originally Posted by ArtDart
When I got my ‘17 Mazda CX-5, I used 87 E10 gas...
The oil level on dipstick kept rising.
I changed the FF @ 1500 mi & started using 91 E0 gas..
Oil level on dipstick has remained rock solid ever since, despite my ultra short tripping usage.
I only fill up once a month, so the additional cost is minimal & worth it to me.
I believe the owners manual says to use a MINIMUM of 87 octane



Higher octane is harder to ignite if anything the opposite should happen.

 

[OVERKILL]

Originally Posted by dave1251
Originally Posted by ArtDart
When I got my ‘17 Mazda CX-5, I used 87 E10 gas...
The oil level on dipstick kept rising.
I changed the FF @ 1500 mi & started using 91 E0 gas..
Oil level on dipstick has remained rock solid ever since, despite my ultra short tripping usage.
I only fill up once a month, so the additional cost is minimal & worth it to me.
I believe the owners manual says to use a MINIMUM of 87 octane



Higher octane is harder to ignite if anything the opposite should happen.


IIRC, the theory tabled on BITOG goes thusly:

On high compression GDI engines (this applies to Port-Injected engines to, but we'll stick to GDI given that's the topic here) enrichment is used to mitigate spark knock and will of course also impact ignition timing. Running premium results in the enrichment being scaled back and more timing advance, which results in less fuel in the oil.

 

[Eddie]

Interesting theory OVERKILL. Is there any data to validate the theory? Ed

 

[OVERKILL]

Originally Posted by Eddie
Interesting theory OVERKILL. Is there any data to validate the theory? Ed


As far as I know, the only data that exists is from folks on this site that have done UOA's with regular and premium and the premium resulted in significantly less fuel dilution.

 

[das_peikko]

Originally Posted by Eddie
Interesting theory OVERKILL. Is there any data to validate the theory? Ed


You're asking OVERKILL for validation (proof) ? You got some guts dude.

 

[HighbrowHillbill]

Originally Posted by OVERKILL
Originally Posted by dave1251
Originally Posted by ArtDart
When I got my ‘17 Mazda CX-5, I used 87 E10 gas...
The oil level on dipstick kept rising.
I changed the FF @ 1500 mi & started using 91 E0 gas..
Oil level on dipstick has remained rock solid ever since, despite my ultra short tripping usage.
I only fill up once a month, so the additional cost is minimal & worth it to me.
I believe the owners manual says to use a MINIMUM of 87 octane



Higher octane is harder to ignite if anything the opposite should happen.


IIRC, the theory tabled on BITOG goes thusly:

On high compression GDI engines (this applies to Port-Injected engines to, but we'll stick to GDI given that's the topic here) enrichment is used to mitigate spark knock and will of course also impact ignition timing. Running premium results in the enrichment being scaled back and more timing advance, which results in less fuel in the oil.

So there are other reasons to run the higher octane besides HP output and 'because we said so'. Good to know.

 

[Ded Mazai]

Your engine may last longer if you use 91 gas. And you may be able to change the oil and the filter less often which offsets the higher cost of gas a little.

 

[spasm3]

Member Pimtac is running 93 in his cx-5 skyactiv engine. He has stated it it runs better on hills etc. I'm going to try a few tanks in my cx-5, as these are 13:1 engines.

 

[BrocLuno]

As the octane goes up, so do the additives. The simplest gas you can get is the cleanest burning.

 

[y_p_w]

Originally Posted by BrocLuno
As the octane goes up, so do the additives. The simplest gas you can get is the cleanest burning.

What? Some octane rating increase is due to oxygenates, but for the most part a similar higher octane fuel simply uses higher octane rated base fuel. The majority of gasoline sold in the US these days has 10% ethanol anyways, so that's kind of the baseline.

I do remember hearing something about Unocal having a patent on some method of making higher octane fuel cheaper, but I don't recall exactly what it was. I do remember a time when 76 stations (before the Tosco purchase) had 89 AKI octane as their basic offering comparable to other 86/87 octane regular.

 

[4WD]

Someone mentioned Infineum not putting additives in and it's already per spec fuel … of course they sell additives upstream of the fuel pump … part of achieving said specs …

 

[y_p_w]

Originally Posted by 4WD
Someone mentioned Infineum not putting additives in and it's already per spec fuel … of course they sell additives upstream of the fuel pump … part of achieving said specs …

Originally Posted by 4WD
Someone mentioned Infineum not putting additives in and it's already per spec fuel … of course they sell additives upstream of the fuel pump … part of achieving said specs …

Who brought up Infineum? I get they still make certain fuel additives to help flow and lubricity, but they don't say they make detergent additives.

 

[nicholas]

Higher octane is NOT harder to ignite......
It resists PRE IGNITION better than 87.

Big difference