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In some Asian Countries like the Philippines, I heard Shell Gasoline there has 97 octane for the V-Power Nitro + Racing, then 95 for Nitro+, the 91 for the fuel save. Then 87 for the regular unleaded. The competitor Petron Gasoline has 100 octane for what they call petron blaze.
 

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sn plus

We already know from the numerous oil tests that all synthetics are not created equal. We also know that it's more than just "the shear argument" that's relevant to DI turbos. So, in a 2.5 ton vehicle with a 2.4L DIT, I personally would look for the best rated oil. YMMV, to each their own, etc... but, short version is, the amount of shear in various tested synthetics varies wildly.

The 505.01 spec is a VW spec, by the way. It also isn't really impressive (link). Now, if you'd mentioned VW 507.00, that'd be different.

Here's an AAA report that shows performance differences between standard and synthetic oils. Of note is that some of the synthetics sheared more than the standard oils tested.
So, yeah, just pouring in some random synthetic oil does not mean less shear than non-synthetic.

All oils are not created equal.

Also, the manual also states this about the oil that should be used - pretty basic, but not relevant to individual brand performance:


Here's some testing comparisons (there's more referenced in the links I posted earlier):
Some light reading:

amazonbasics Full Synthetic dexos10W-20SNResource Conserving, SN PlusGF-5 https://engineoil.api.org/Directory/EolcsResultsDetail?companyId=10297
 

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We already know from the numerous oil tests that all synthetics are not created equal. We also know that it's more than just "the shear argument" that's relevant to DI turbos. So, in a 2.5 ton vehicle with a 2.4L DIT, I personally would look for the best rated oil. YMMV, to each their own, etc... but, short version is, the amount of shear in various tested synthetics varies wildly.

The 505.01 spec is a VW spec, by the way. It also isn't really impressive (link). Now, if you'd mentioned VW 507.00, that'd be different.

Here's an AAA report that shows performance differences between standard and synthetic oils. Of note is that some of the synthetics sheared more than the standard oils tested.
So, yeah, just pouring in some random synthetic oil does not mean less shear than non-synthetic.

All oils are not created equal.

Also, the manual also states this about the oil that should be used - pretty basic, but not relevant to individual brand performance:


Here's some testing comparisons (there's more referenced in the links I posted earlier):
Some light reading:

https://www.amazon.com/AmazonBasics-Full-Synthetic-Motor-dexos1-Gen2/dp/B07CG384GQ/ref=sr_1_3?keywords=sn+plus+0-20+oil&qid=1557342704&s=gateway&sr=8-3
 

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Little side comment here. Not ascent related but can apply. The 2.0 in the crosstrek I get around 26mpg with regular. With 93 I can get 30-31 on the exact same style of driving. Don’t think the engine knows the difference but I guess it’s because the thing cuts so much timing for knock.

Just a observation on another Subaru that maybe someone can do a good comparison of the 2 fuels on an ascent.
 

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I consistently see slightly worse gas mileage and a very slight (possibility imaginary) feeling of it being a little smoother when running 93.

Maybe I'll 0-60 it one day.

But, on the Subaru turbo motors, there's nothing in the programming that would allow a similar benefit.


Little side comment here. Not ascent related but can apply. The 2.0 in the crosstrek I get around 26mpg with regular. With 93 I can get 30-31 on the exact same style of driving. Don’t think the engine knows the difference but I guess it’s because the thing cuts so much timing for knock.

Just a observation on another Subaru that maybe someone can do a good comparison of the 2 fuels on an ascent.
 

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Shell *93* has the highest of the brands tested.

Here is the AAA fuel quality report. http://newsroom.aaa.com/wp-content/uploads/2016/06/Fuel-Quality-Full-Report-FINAL-1.pdf However I cannot find whos gas uses the detergents that keep the valves the cleanest. Just that top tier detergent gas is in fact better for your engine.
It's in the forums. It's Shell 93, by a wide margin. Even beats their 87 and 91 octanes. I did a list here:
 

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I consistently see slightly worse gas mileage and a very slight (possibility imaginary) feeling of it being a little smoother when running 93.

Maybe I'll 0-60 it one day.

But, on the Subaru turbo motors, there's nothing in the programming that would allow a similar benefit.
You should keep in mind the ECU is going to be slower to respond to 93 as there is no immediate danger due to knocking or predetonation in going up in octane vs going down. If Subaru has stayed consistent with previous ECU tuning, idk either way and apparently noone does at this point, the timing compensation slowly increases the dynamic advance multiplier (DAM) as no knock incidents are reported. As soon as consistent knock is present or multiplier is maxed out, then the ECU stops or maxes out timing.

Too think there are never any knock events on a stock engine is a quite interesting theory. How would the ecu ever maintain performance if it wasn't constantly "testing" fuel quality in the form of timing advance and knock events?

I can confirm in other dit and turbo subarus a stage 0 tune can definitely add power and torque via added boost, timing, and fuel mapping. The important thing is to be consistent with the fuel you are tuned on.
 

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We agree...

You should keep in mind the ECU is going to be slower to respond to 93 as there is no immediate danger due to knocking or predetonation in going up in octane vs going down. If Subaru has stayed consistent with previous ECU tuning, idk either way and apparently noone does at this point, the timing compensation slowly increases the dynamic advance multiplier (DAM) as no knock incidents are reported. As soon as consistent knock is present or multiplier is maxed out, then the ECU stops or maxes out timing.

Too think there are never any knock events on a stock engine is a quite interesting theory. How would the ecu ever maintain performance if it wasn't constantly "testing" fuel quality in the form of timing advance and knock events?

I can confirm in other dit and turbo subarus a stage 0 tune can definitely add power and torque via added boost, timing, and fuel mapping. The important thing is to be consistent with the fuel you are tuned on.
I don't think either of us said anything about there being zero knock. There'd be no timing changes to address knock if there was no knock :tango_face_wink:

And, we already addressed what a tune could do, someplace earlier, and, we've been bugging COBB for a while about it. Now that the Leggy and OB are getting XT models with the FA24DIT, we expect it will happen soon.

That's all buried someplace in the 25 pages above, and easy to miss, but, short version is, yeah, we agree with all of that. :grin:
 

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I didn't see any discussion in the previous pages specifically about Subarus timing compensation strategies in just about every other vehicle they make. Just a lot of mentions about what the manual states about required fuel. And a few posts specifically stating, "if 87 is in the manual it wont knock on 87". There was a gentleman, pilot1226 may recall this post on legacygt.com, that did some datalogging with freessm iirc on an ascent and he seemed to think the timing strategy was basically what Subaru has been doing all along, kind of running on the ragged edge of lean.
I will find and link that post it was an interesting read.

I am very curious to see what some of the more dedicated tuners come up with as this engine grows in popularity. My wife loves it and that is about all that matters in this household, lol. We are using 93 as well, we are only at around 900 miles.
 

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I didn't see any discussion in the previous pages specifically about Subarus timing compensation strategies in just about every other vehicle they make. Just a lot of mentions about what the manual states about required fuel. And a few posts specifically stating, "if 87 is in the manual it wont knock on 87". There was a gentleman, pilot1226 may recall this post on legacygt.com, that did some datalogging with freessm iirc on an ascent and he seemed to think the timing strategy was basically what Subaru has been doing all along, kind of running on the ragged edge of lean.
I will find and link that post it was an interesting read.

I am very curious to see what some of the more dedicated tuners come up with as this engine grows in popularity. My wife loves it and that is about all that matters in this household, lol. We are using 93 as well, we are only at around 900 miles.
I'm on my 3rd tank of 93 for this go round. I am switching back to 87. 93 still "feels" "smoother" but actually seems to perform slower. And this time, I'm going to do some 0-60 runs using Torque.
 

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always go with has been recommended because rarely will you ever find that there will be any noticeable gain in power or even fuel economy. Its only when you go for really high octane fuel on a tuned engine that real changes happen.
I have contacted today the customer relations department of Subaru America I have a similar problem whereas I've driven only 1815 miles on a brand new 2019 Subaru Ascent touring and I can't get past 14.5 MPG when 75% of my driving has been Highway and 25% City a far cry from the 23 and 27 sticker MPG display I was actually told it would be closer to 30 I believe there has to be a fueling or emissions issue because I cannot believe this Subaru what do false advertising unless of course the car is just a lemon we will see how they Remedy Our dissatisfaction other than that I thought the car was absolutely a great value and phenomenal but this problem must be fixed and remedied in our favor immediately
 

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Regular 87? In Colorado regular is 85
I bought my Ascent in Colorado Springs, drove up to Wyoming, filled it with 85° and noticed my estimated miles on a tank had dropped from the 440 mile estimate shown when I took delivery. I then read in the owner's manual that 85° is not recommended for use in high elevation states. I've filled it with 87° or higher (Sam's only has 85° or 91°) since then.
 

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I've been on 93 for about 6000 miles straight. I've drive about 4000 since the warm weather has reached NY. Computer shows 24.6 mpg and I've been driving the car like I stole it.
 

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I wanted to find what type of gas is recommended in Subaru? I am coming from the last 4 cars going back to 2010 that required Premium gas. I am hoping to finally get into a car that uses regular
First, I was really concerned about fuel consumption. As per Subaru Manual, use 87 or higher, that is it, it is NOT 87, it is 87 and UP. In my experience (2020 Ascent premium) premium grade is better in total tank mileage, 260 vs 310+ on premium. Also, Premium grade fuel has more additives that help to preserve the engine/pistons, so paying $5-6 more gives me 40-60 miles more. Try both ways and see which one is better for you. But make sure your car has gone through the break-in period first.

I wanted to find what type of gas is recommended in Subaru? I am coming from the last 4 cars going back to 2010 that required Premium gas. I am hoping to finally get into a car that uses regular
 

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First, I was really concerned about fuel consumption. As per Subaru Manual, use 87 or higher, that is it, it is NOT 87, it is 87 and UP. In my experience (2020 Ascent premium) premium grade is better in total tank mileage, 260 vs 310+ on premium. Also, Premium grade fuel has more additives that help to preserve the engine/pistons, so paying $5-6 more gives me 40-60 miles more. Try both ways and see which one is better for you. But make sure your car has gone through the break-in period first.
It has already been proven anything higher than 87 server zero purpose in performance (gas mileage, power or otherwise.)
The stock ECU map cannot take advantage of higher than 87 octane fuel.
So assuming what you’re saying isn’t placebo or erroneous, your 87 gas must be something awful.
 

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It's interesting to note what the new Mazda 2.5 Litre turbo does.. it's rated at 250 HP with 310 Lbft torque as long as you use 93 octane fuel. The engine will adjust if you use 87 octane to 227 HP but the torque remains the same at 310. The 310 torque occurs early in the rpm range and therefore most drivers don't notice the difference between 87 and 93 fuels. Very interesting technology. My wife is interested in the CX5 which has this engine as optional. It does 0-60 in 6.1 seconds. Pretty good considering it looks the same size as a Forester. It may be the quickest vehicle in that segment excluding the luxury SUV's.
 

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It has already been proven anything higher than 87 server zero purpose in performance (gas mileage, power or otherwise.)
The stock ECU map cannot take advantage of higher than 87 octane fuel.
So assuming what you’re saying isn’t placebo or erroneous, your 87 gas must be something awful.
This is funny what you are saying to me))) gas grade does play a role with almost every engine - and this is a fact! put bad gas in and put good gas in and test - then talk here. Theories do not always work in practice! You can Prove if you can by sharing the link for the study or smth. But I was sharing my personal experience, unlike you, basing it on whatever and I saw that premium gas gave me 40+ miles more than regular. Believe it or not, I don't care, but this is a fact for me! FYI my car is brand new 1500 miles on it only and my mileage went from 13.4 to 19mpg as of yesterday. Also, I did the reprogramming thing yesterday also, but it is not for this thread.
 

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My proof happens to be the best Subaru tuning company there is testing this very thing on the Ascent over months. The stock ECU map is not dynamic like most cars that can take advantage of higher octanes. Fact.
Your particular experience points to your particular 87 octane gas being particularly awful in quality, if you’re actually seeing a difference in mileage.
Pretty simple stuff. Fuel octane and fuel quality are 2 very different things.
 
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