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Discussion Starter #1
Hi,

I just bought my second Crosstrek a week ago, a 2015 2.0i Basic, w/a 5 M/T. I had gotten rid of my '14 Crosstrek a few months ago, and started missing it.

I've got well over 1500 miles on it as of today, taking it easy breaking it in. I just went and switch it over to High Test/Premium gasoline (92 Octane) today, and started noticing an improvement in performance, just like I did when I did it to my '14 Crosstrek, when I ran it in it. I'm not talking mind blowing performance mine you, but still noticeable. Done in two different vehicle can't be just my imagination.

The only draw back, a small loss in mileage. I estimate I lost about 2 mpg or so. I was getting around 35 doing 60 mph, w/regular, and now I'm getting a little over 33. I have to do more driving in order to confirm that.

I know some of todays engines, like the Ford Eco Engines for example, can run on either 87 or High Test/Premium , w/the High Test/Premium providing the better engine performance, thanks due to today's computer systems in them.

The 2.0L engine in the Crosstrek and Impreza, has a 10.5:1 compression ration, making it a high compression engine. Most engines w/that compression require High Test/Premium fuel. With the computer system in the Subaru, one has to figure that it too can compensate for the fuel difference.

The reasoning I figure, Subaru is trying to get the Crosstrek and Impreza to meet a particular fuel mileage. In doing so, they use a very light weight oil, 0W-20, and a low octane fuel.

When it comes to the factory oil, I thought I read somewhere that the oil in the Subaru's 2.0L engine from the factory is a 5W-30. Anyone know if this true?

Anyway, has anyone else tried using High Test/Premium gasoline in their Crosstrek, and what's your feeling about it?
 

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Others have and swear by it. I've tried it for a few tanks and didn't find too much of a difference. In Canada, going high test is going high price as the difference between regular and premium can be more than 65 cents per gallon!

From what I read, Subarus in general like the higher octane stuff as the engine but for the lower price ranges, they scale back on what the requirements of the car are so that they don't turn off some buyers.

According to some oil analysis posted on other forums, the factory fill may be 5w-20. As with most cars sold in North America, the use of 0w-20 is probably due to the OEMs trying to squeeze as much fuel economy out of the engine as possible in other to meet CAFE levels. Some other OEMs have switched from 5w-20 to 0w-20 using the same engine in order to squeeze a bit more fuel economy out of the design. For the FB20, many markets outside of North America use a thicker grade of oil as their recommended weight.
 

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Discussion Starter #3 (Edited)
I also own an '06 Honda Element, AWD, w/a 5 Spd M/T, and I tried running High Test in it, w/no results there. In fact I think it even hurt the performance, so I never tried it again in it.

As for the Crosstrek, on the other hand, I definitely noticed an improvement using it in it.

What's the oil weight requirement for Canadian Crosstreks?

In such places as Yuma, AZ. where temperatures can reach 117F plus, I would definitely not use 0W-20/5W-20 synthetic, but rather a 5W-30 synthetic. Even here in the NW, where the temperatures have been running over 90F this summer, makes me nervous using such a light weight oil as 0W-20.
 

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In order to benefit from higher octane fuel, an engine has to be built for it. The Crosstrek's engine isn't. That 2mpg lower could very well come from it being driven more spiritedly. The only performance improvement from using a higher octane would be due to a lighter wallet. If an engine isn't pinging, higher octane won't be any improvement unless it doesn't have ethanol and regular does. In that case, fuel economy will be a little better, but not enough to make up for the cost difference.
 

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I'm with Pat on this one. Use what the book says.
 
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Discussion Starter #6
All I know is, when I hit the throttle, I notice less lag when getting the car moving, using the higher octane fuel. Again, I'm not talking a lot, but definitely noticeable. With the low octane, I tend to have to downshift more. We're talking about a manual here and not a CVT.

Then as I stated, I tried using high octane fuel in my Honda Element, and it definitely didn't do any good there, so I don't see this as simply a figment of my imagination. This is also my second Crosstrek, which I ran high test in, so here we have two Subaru's showing positive results, while my Honda doesn't.

The 2 mpg difference was w/cruise control locked in.

If I use high octane anywhere, it'll be when I tow my trailer w/my Crosstrek.
 

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During my road-trip in May, I used premium fuel because it was so cheap in Wyoming. It ran a little smoother and on two consecutive tanks, I achieved over 40mpg. Keep in mind that was about 7500-8500 ft elevation. Haven't used it since I got back since it's not worth the extra cost IMO.

As with most new cars built for economy today, oil requirements are for 0/20W so is nothing new. My '05 Honda Civic Hyrid called for 0-20W and it worked great.
 

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Unless your car was having knock issues, no benefit to premium in a car like the XV. I am afraid this is another case of Butt Dyno failure. Here are some articles for you...

http://m.caranddriver.com/features/regular-or-premium

Using Premium Gas Often A Waste Of Money - Business Insider

Edit: You mention Ford's Eco engines running better on premium. First of all, it is EcoBoost. Second, the presence of a turbo is the reason they run better on premium. Modern ECU allows the car to run on regular with a power loss penalty. Not that long ago EcoBoost cars would have been premium only cars. Engine tech has allowed them a little additional fuel flexibility.
 

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I use Shell V-Power Premium fuel, it has engine cleaners and does not contain ethanol. I also use Pennzoil Platinum oil 0w-20. The vehicle runs great. I used the v-power in my forester and never had to worry about dirty injectors.
 

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I use Shell V-Power Premium fuel, it has engine cleaners and does not contain ethanol. I also use Pennzoil Platinum oil 0w-20. The vehicle runs great. I used the v-power in my forester and never had to worry about dirty injectors.
Do what makes you feel better, but this is mostly a placebo effect. Premium gas and reglar both have a required level of detergents. Shell will advertise additional detergents, but look into it and you will find little support for using the additional additives. The only real benefit to your fuel choice is the ethanol free part.

While I don't think it is a concern for the XV, I know for a fact that the quality of fuel for the same brand and same octane level can vary by gas station. I used to swear by Shell 93 octane in my Focus ST. I moved to a different city and my data logs showed the car was pulling a little timing. Switched to BP 93 octane and problem solved. Did a little reading and found out from reputable tuners that quality variations like this exist.

Paying a Premium for High Octane Gasoline? | Consumer Information
 
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I agree with GoHack on this.

I have experienced exactly what is described in the original post in my 14" Limited. On light throttle under load say cruising through a park at 25 Mph I have had some noticeable knocking with 87 octane. Switched to 89 octane and the knocking was gone and felt as is the engine "smoothed" out. No More power per se, but power delivered smoother. I also heard that a higher octane fuel is less efficient.
 

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If you are experiencing enough knock with regular that you need to use a higher grade, you should probably have your car looked at IMO.
 
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She has been serviced regularly and i have made mention of it.

It happens so infrequently and just a slight knock more of a ping that alost anyone else wouldn't notice it.

I am a bit of a hypoCARndriac and listen very close to what she is doing and saying.
 

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Shell is a Top-Tier fuel. Top Tier Gasoline
To get that rating, it had to pass tests to prove it had a quality additive package of cleaners in all grades. You don't get a cleaner engine with more expensive grades.
 

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While I had my 13 XV I did extensive testing under what I considered as controlled as any real world conditions allow and found by running higher octane did make my XV run a little smoother while averaging 1/2 mpg better. Was it cost effective no but I enjoyed the smoother acceleration. If you want details go to my Testing Testing thread and start from the beginning.
 

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While I had my 13 XV I did extensive testing under what I considered as controlled as any real world conditions allow and found by running higher octane did make my XV run a little smoother while averaging 1/2 mpg better. Was it cost effective no but I enjoyed the smoother acceleration. If you want details go to my Testing Testing thread and start from the beginning.
Define extensive testing a little further... Unless it was extensive enough to include monitoring engine parameters (like knock count) and/or dyno numbers, then it is still susceptible to your butt dyno. As I have stated before butt dyno's tend to suffer from a rather severe calibration error.

No offense intended to anyone here with any of the comments I have posted. I just want to be clear that we have yet to see any instrumented test proof that premium fuel helps in the XV. We only have a few people who think it works. If you think it works and you want to do it, go for it. I just don't want someone who is new to this coming in, seeing your subjective opinion, and counting your opinion as fact. The facts we do have suggest that no improvement could be expected unless your vehicle was having knock issues.
 

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Those willing to risk their preconceptions with an actual test can do this without any test equipment or expertise. Have somebody else fill the tank so you don't know what grade of fuel you're using. Then critique the experience for the different fills. Use the same grade for at least a few fills so you aren't critiquing a fuel mix. Those who are in the "my mind is made up so don't confuse me with the facts" camp needn't bother. I'm sure more butt dyno reports will follow anyway but I tried here at least.
 

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Discussion Starter #18 (Edited)
Unless your car was having knock issues, no benefit to premium in a car like the XV. I am afraid this is another case of Butt Dyno failure. Here are some articles for you...

Regular or Premium? - Feature - Car and Driver

Using Premium Gas Often A Waste Of Money - Business Insider

Edit: You mention Ford's Eco engines running better on premium. First of all, it is EcoBoost. Second, the presence of a turbo is the reason they run better on premium. Modern ECU allows the car to run on regular with a power loss penalty. Not that long ago EcoBoost cars would have been premium only cars. Engine tech has allowed them a little additional fuel flexibility.
If this were indeed true, then why didn't I feel the same Butt Dyno thing w/my Honda Element, when I ran High Test/Premium in it?

Once again, the ECU in the Subaru can't do the same thing when it comes to running High Test/Premium on the 2.0L engine, as in the ST's? I realize the 2.0L in the Crosstrek is a non-aspirated engine, but there has to be some amount of corrections allowed when it comes to using different kinds of fuels, be it 85, 87, 89, 90+, and fuels w/ethanol. The quality of the fuels now-a-days, aren't what they use to be, when it comes to the actual octane rating, and even the amount of ethanol truly in the fuel, at the pump.

As for the Ford's EcoBoost engines, yes I realize they do better on premium, mainly thanks to the turbo and the ECU, but they also can run steadily on regular fuel as well, w/a loss of power of course.

As for the performance/cost factor when it comes to using High Test/Premium in the Crosstrek, you may be right. On the other hand, when it comes to such things like towing a trailer, or even extremely hot outside temperatures, it may be an advantage.
 

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Define extensive testing a little further... Unless it was extensive enough to include monitoring engine parameters (like knock count) and/or dyno numbers, then it is still susceptible to your butt dyno. As I have stated before butt dyno's tend to suffer from a rather severe calibration error.

No offense intended to anyone here with any of the comments I have posted. I just want to be clear that we have yet to see any instrumented test proof that premium fuel helps in the XV. We only have a few people who think it works. If you think it works and you want to do it, go for it. I just don't want someone who is new to this coming in, seeing your subjective opinion, and counting your opinion as fact. The facts we do have suggest that no improvement could be expected unless your vehicle was having knock issues.
If you go to my 1st post you will see how I was doing my testing which was only to prove to myself if there was any improvement and stating the results. In real world driving I believe if you gas up at approx. same time, same day every week at same station and same pump ( kick off back pressure can vary between pumps ) you can have a reasonable assumption you are getting as accurate results as possible without being scientific about it. I purchased the XV with economy being one of the main reasons and drove each week trying to maximize mileage. As for the Butt dyno susceptibility I never floored the car or had it over 4000 rpm. When I wanted to have fun driving I had a 07 Cobb tuned Spec. B. for that. Whatever car I drive I drive it for the purpose it was made for. I am sure you know that modern engines are made to closer tolerances than the engines of years ago but not all engines are created equally. Therefore the engines computer can compensate within certain parameters for the small differences Subaru deems permissible for engine performance.
 

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I'll chime in. I logged everything in my 2011 Ford Fiesta. Just a high compression NA 1.6L. Over three years, and 110,000 miles, I watched. Over that time, any time I ran regular, it cost me $0.14 per mile. With premium, it cost $0.11 per mile. That saved me about $10.50 per tank, and it cost me about $2.00 more to fill up. I also tracked knock. With regular, under extreme conditions (mostly climbing a large hill in 100+ degree heat), I would rarely notice a knock. With premium, I never saw a knock.

I have NOT run anything but premium in the XV since I've owned it. I will. Once I'm done modding it and can get a steady mpg reading , without influence of and mpg-robbing mods.
 
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