Consensus on Premium gas for Skyactiv

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I just refilled with Shell 93 after reading some of the threads on the Skyactiv engine and fuel type. I'm not sure I buy the idea that it helps reduce fuel dilution, but I suppose it's possible.

Is there any consensus to date that suggests it is better? Can it do any harm other than just cost you more money?

Manual says 87 or higher I believe...
 
It will cost you less money and reduce fueldilution in the oil.

Lower octane gas is more prone to detonation. To avoid pinging the engine will have to overfuel. This will hurt gas mileage and put extra fuel in the pil.

My parents switched to 91/93 on their escape gtdi. It gets significantly better economy and has more power ... which means the transmission also isn't wearing itself out by constantly shifting.

It comes down to saving something like a savings of $5 per 1000 miles for them.


Edit: had to buy a book on gdi for my father to run 91 octane in it.
 
Use what the manual recommends; the whole fuel dilution "problem" is a non issue. If any car should have a problem it would be my MS3. I'm running a tune that goes very rich at full throttle to avoid knock and I have yet to receive a UOA which indicates there is any problem with fuel dilution.

And for the record, I've had 22 UOAs performed over the 146,000 miles I've owned the car...

If the Skyactiv does return better fuel economy/performance running 93 then I would consider it, but I doubt that would be the case based on Mazda's recommendation of "87 or higher" fuel.
 
Originally Posted By: MCompact
Use what the manual recommends; the whole fuel dilution "problem" is a non issue. If any car should have a problem it would be my MS3. I'm running a tune that goes very rich at full throttle to avoid knock and I have yet to receive a UOA which indicates there is any problem with fuel dilution.

And for the record, I've had 22 UOAs performed over the 146,000 miles I've owned the car...
Your MS3 doesn't have direct injection.
 
Originally Posted By: xxch4osxx
Your MS3 doesn't have direct injection.


Thanks for the heads-up!
That would be an extremely helpful observation except for the salient fact that it is 100% wrong...
 
My wife owned a 2012 Mazda3 with the Skyactiv engine but just traded it in for an Audi A4. Her Mazda did seem to make more power on higher octane than using regular 87 octane. Or more like the engine had a better feel to it using higher octane.

Mazda supposedly told the auto press that the North American Skyactiv engines have 1 point lower compression vs Europe due to us being addicted to 87 octane. The UK Mazda3 does indeed have 1 point higher compression.
 
Originally Posted By: MCompact
Originally Posted By: xxch4osxx
Your MS3 doesn't have direct injection.


Thanks for the heads-up!
That would be an extremely helpful observation except for the salient fact that it is 100% wrong...
I was under the impression that 2007 models did not have direct injection.
 
Sorry about yanking your chain. All the 2006-up turbos are DI- and there was a steep learning curve in the tuner community, a lot of ZZB(Zoom-Zoom-BOOM!) until the tuners got a handle on the new technology. A few cars are now making over 500 hp with big turbos and E85. Me, I have enough trouble putting 300 hp through the front wheels- can't imagine dealing with 200 more ponies in anything other than a straight line...
 
Originally Posted By: MCompact
Sorry about yanking your chain. All the 2006-up turbos are DI- and there was a steep learning curve in the tuner community, a lot of ZZB(Zoom-Zoom-BOOM!) until the tuners got a handle on the new technology. A few cars are now making over 500 hp with big turbos and E85. Me, I have enough trouble putting 300 hp through the front wheels- can't imagine dealing with 200 more ponies in anything other than a straight line...
Ah yes, the turbo models. Interesting to know about that! I can imagine 500hp must put alot of strain on the transmission and CV joints as well.
 
I have also tried a couple of times using a few consecutive tanks of premium in my 2012 Sky. If there was any power difference I'd need a dyno because, apparently, my butt's not calibrated. I saw no benefit to the fuel economy and I guess I don't worry about fuel dilution. I've never even done a UOA in thirty years of driving.

This has to be at least the tenth thread I've seen on this topic this year. I doubt there will be any real conclusion until somebody sponsors a REAL set of valid tests and not just "it felt more powerful."
 
I haven't noticed any power improvement. I'm curious about whether it helps fuel dilution.
 
For those who run on the "+" side of 87+ AKI, why is it that you always go straight to 93 AKI?? Why not 89, 91 or 92 AKI? "Premium" for Subarus at least, is 91 AKI, though 93 does provide a noted improvement. I can't imagine running 93 in an 87+ engine.
 
Originally Posted By: gathermewool
For those who run on the "+" side of 87+ AKI, why is it that you always go straight to 93 AKI?? Why not 89, 91 or 92 AKI? "Premium" for Subarus at least, is 91 AKI, though 93 does provide a noted improvement. I can't imagine running 93 in an 87+ engine.


Depends on what is available. Sam's Club around here only has 87 and 93
 
I have a 2014 CX5 and tried 91 vs 87
and kept fuel mileage records for 2 full tanks of each and any increase or decrease was buried in the variability of tank to tank values. I therefore see no reason to run higher than 87.
 
I've seen a lot of posts in two years about the fuel dilution. Either my car is burning exactly the amount of oil being replaced by fuel, or the amount of fuel getting into the oil is negligible. The level on my dipstick has remained unchanged for 18,000 miles. I am running the microGreen OCI of 30,000 miles with three filters. I'll do my first UOA afterward to see if I wore out the oil. I am using M1 0W-20 AFE.
 
Originally Posted By: DBMaster
I've seen a lot of posts in two years about the fuel dilution. Either my car is burning exactly the amount of oil being replaced by fuel, or the amount of fuel getting into the oil is negligible. The level on my dipstick has remained unchanged for 18,000 miles. I am running the microGreen OCI of 30,000 miles with three filters. I'll do my first UOA afterward to see if I wore out the oil. I am using M1 0W-20 AFE.


You have a misconception of what fuel dilution does. It doesn't add any level to the sump. It degrades the viscosity and flash point of the oil.
 
Originally Posted By: buster
I just refilled with Shell 93 after reading some of the threads on the Skyactiv engine and fuel type. I'm not sure I buy the idea that it helps reduce fuel dilution, but I suppose it's possible.

Is there any consensus to date that suggests it is better? Can it do any harm other than just cost you more money?

Manual says 87 or higher I believe...


My UOAs have proven to me it eliminated fuel dilution issues for me. I averaged about 38-39 MPGs when I was using 87 octane and since switching to 91+, my average MPGs for the same commute are always between 43-44 MPGs during the summer and 40-41 during the winter.

Does fuel dilution cause harm? No evidence that it does at this point but I prefer to get the best MPGs I can and have my oil stay in grade viscosity wise.

There are also dyno tests out there showing a marginal increase in HP using premium on a skyactiv. There are also ODB readouts showing advances in timing using premium.
 
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Originally Posted By: badtlc
DBMaster said:
You have a misconception of what fuel dilution does. It doesn't add any level to the sump. It degrades the viscosity and flash point of the oil.


Apparently so. I was confused because I had read an article last year about the Skyactiv diesels in Europe coming back to the dealers with increasing oil levels due to fuel. When I do my UOA I am going to find a lab other than Blackstone that both includes TBN and uses a different method for measuring fuel content - for one fixed price. I found several options when doing a casual search. I'm 2,000 miles from the next filter change. After that, 10,000 more miles and then the oil gets changed. Should be interesting.
 
I'm a 1/4 tank into this latest fill of premium Shell. I hit 38.3 mpg. Highest yet. I was driving slow though. Car has 690 miles on it.

I'm going to have my wife put premium in her 3 with the 2.5L and see if she gets better mpg.
 
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