Subaru Outback Forums banner

1 - 20 of 156 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
So I bought a 2020 Subaru Onyx XT. Still have a half tank of gas, but going to a fill up probably this weekend. Just wondering about people thoughts on using premium versus regular unleaded gasoline. What about mid-grade? I know there are benefits to using premium gas.
 

·
SubaruOutback.org Founder
2018 Outback Limited 2.5L - 100,000+ miles
Joined
·
4,966 Posts
It is unnecessary to use any fuel with octane higher than 87. That being said there has been plenty of discussion on how higher octane fuel may lessen issues commonly experienced with direct injection engines. I will let more knowledgeable people share their thoughts on that matter.
 

·
Registered
Joined
·
5,520 Posts
What benefits do you know? The car is supposedly tuned for regular octane. I doubt Subaru has engineered the vehicle to gain any benefit from premium fuel.
 
  • Like
Reactions: seinberg

·
Registered
2020 Outback Touring XT
Joined
·
193 Posts
As I understand it, higher octane ratings are intended for engines with higher compression. Most of my experience on this topic is related to motorcycles, but don't know why it wouldn't carry over to car engines too. Using gasoline with a higher than recommended octane rating is generally not going to provide any benefit, and obviously it will cost you more. I have no intention on putting anything other than 87 octane in my Touring XT.
 

·
Registered
Joined
·
411 Posts
The point of the 2.4 DIT over the 2.0 DIT is being able to use regular fuel. A decent brand, such as Sunoco, has detergents in all of their fuels.
 

·
Registered
Joined
·
2 Posts
Try to find ethanol-free gas - problem around where I live is that only 91 octane is available ethanol-free.
 

·
Registered
2015 3.6R Limited w/ES
Joined
·
3,004 Posts
Plenty of discussion on the topic all over these, and other, forums. I've never seen a shred of convincing evidence that there's much, if anything, to be gained from higher octane on a stock tune. But there has been a fair amount of data posted from tuners that show it's possible to see some benefits, even in NA engines.
 

·
Registered
2019 2.5i Limited Forester (hers) (4th Subie), 2014 Impreza Premium (mine)(#5)
Joined
·
2,297 Posts
Try to find ethanol-free gas - problem around where I live is that only 91 octane is available ethanol-free.
We have plenty of both down here. The cars will have a slight (1 - 2) mpg decrease using E10 versus 100% gas, but that's it.
 

·
Registered
Joined
·
288 Posts
Someone mentioned online that premium gas is needed in hot climates. I live in Texas where 100 is the norm in the summer.
This is discouraging since one of the attractions was the use of regular gas..I now drive an MDX which requires premium.
 

·
Registered
Joined
·
4,903 Posts
In general the octane requirements go up when:
Humidity is lower
Ambient temperature is higher
Altitude is lower

The engine is designed to use 87, which should be fine, but in some extremes you might have to use something with a little higher octane rating.
 

·
Registered
Joined
·
15 Posts
Higher octane supports higher compression pressures in the block by not igniting until a higher temperature. Lower octane ignites more readily at a lower temperature. Thus high octane fuels are typically only required for blocks that develop high compression. Choosing between high and normal octane fuels isn't usually optional -- you can get pinging or fouling if you don't use the right fuel for the engine -- but the symptoms are pretty obvious. I lived four years with an Outback in Dallas and never even had to think about premium fuel. You shouldn't either. It takes a heck of a lot of ambient heat to do more than a hot engine block is going to do anyway. Get standard and be happy. If you think you need premium, you probably have a problem with your engine.
 

·
Registered
Joined
·
288 Posts
Higher octane supports higher compression pressures in the block by not igniting until a higher temperature. Lower octane ignites more readily at a lower temperature. Thus high octane fuels are typically only required for blocks that develop high compression. Choosing between high and normal octane fuels isn't usually optional -- you can get pinging or fouling if you don't use the right fuel for the engine -- but the symptoms are pretty obvious. I lived four years with an Outback in Dallas and never even had to think about premium fuel. You shouldn't either. It takes a heck of a lot of ambient heat to do more than a hot engine block is going to do anyway. Get standard and be happy. If you think you need premium, you probably have a problem with your engine.
Thanks....Where in Dallas?..I am in McKinney
 

·
Registered
2020 Outback Limited XT Black on Ivory
Joined
·
1,635 Posts
So I know Subaru says regular gas is fine for the 2.4 Turbo but I wonder if premium would deliver more Umph/ MPG/ lifespan. This is my first Turbo vehicle but I have had several other naturally aspirated vehicles in the past that ran better and/or gave me better mileage by regularly stepping up at the pump. Has anyone tried running some level of Premium in their late model XT or know of some test info out there? A net search has produced nothing for me.
I'm wondering if there is any value in trying it on this one.
 

·
Registered
2020 Outback Limited XT
Joined
·
92 Posts
No value to premium fuel in the 2.4DIT, but would recommend top tier fuel for higher quality and better additives.

Coming from a Forester XT that did require premium, I’m enjoying the lower gas bill with similar power.
 

·
Registered
2014 Outback 2.5i
Joined
·
65 Posts
Not sure if all are same, but Shell Canada boasts their 89 has less ethanol and 91 is E0. Is there any benefit to removing corn from the XT's diet?

If not, we'll have to wait for Accessport. :) My 05 Forester XT also wanted 91 and was very expensive to run. That drove me to 2.5 NA Outback, but I'm very tempted by new XT. :)

Sent from my SM-A530W using Tapatalk
 

·
Registered
Joined
·
538 Posts
As noted premium fuel is not needed but the “top tier” fuel additives help keep the injectors clean but DO NOT do anything for the values as it is a direct inject engine (meaning the fuel does not spray on top of the values to which normally keeps them clean. The fuel sprays directly into the combustion chamber. )

As an FYI, Direct Injection puts greater need to make sure you change oil per recommendations to help keep values clean.
 
1 - 20 of 156 Posts
Top