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something else forever
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3,897 Posts
Hi,

I just registered, since I'm considering a WRX to replace my BMW 3-series.

I hate to go against the tide for my very first post :eek: , but I've been using 87 in my cars for years, ever since I read this:
USATODAY.com - Why use premium gas when regular will do?

I thought if it's good enough for engineers from SAE and Porsche, I should be good.
hey bud! :)

so first... try to write your own new thread so that you can properly introduce yourself to everyone on the forums around here... :D

secondly... to each their own... I have ALWAYS put shell v-power 93 into my cars and will continue to do that until something better comes along my way...

good luck and welcome! :D
 

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Premium Member
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4,856 Posts
Hi,

I just registered, since I'm considering a WRX to replace my BMW 3-series.

I hate to go against the tide for my very first post :eek: , but I've been using 87 in my cars for years, ever since I read this:
USATODAY.com - Why use premium gas when regular will do?

I thought if it's good enough for engineers from SAE and Porsche, I should be good.
Do what the manual says. If it says premium recommended, then use premium for best performance but not required. When your manual says required, there's a reason why you shouldn't put anything less then what it says is minimum

Someone put 87 octane in a 12 or 13 3 series bmw at my dealership, engine knock the next day
 

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Premium Member
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10,806 Posts
Hi,

I just registered, since I'm considering a WRX to replace my BMW 3-series.

I hate to go against the tide for my very first post :eek: , but I've been using 87 in my cars for years, ever since I read this:
USATODAY.com - Why use premium gas when regular will do?

I thought if it's good enough for engineers from SAE and Porsche, I should be good.
Anyone who has any time working around cars will tell you lower octane than required will cause long term damage. Maybe not right away but it will.

My understanding is this.

Cars sold in the us must be able to run on any fuel(gasoline) available for emergency purposes. This does not mean run 87 in a high compression motor all the time. It will ping, it may not sound like much but its enough to cause serious damage. The engine requires 91 plus octane to run optimally, make the appropriate power, and not destruct itself.

You must have an old BMW, because when you take it in for service they scan tool the system. If it shows timing is way jacked because the engine is trying to prevent knock they will check it and will void the entire warranty. I know this for a fact as I know a lady who walked down that path with them.

Edit: I just read more of that article akr has nothing to do with power, it has to do with preventing preignition and blowing crap up. Man, that article is so full of incorrect information and speculation is sickening.
 

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something else forever
Joined
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3,897 Posts
Anyone who has any time working around cars will tell you lower octane than required will cause long term damage. Maybe not right away but it will.

My understanding is this.

Cars sold in the us must be able to run on any fuel(gasoline) available for emergency purposes. This does not mean run 87 in a high compression motor all the time. It will ping, it may not sound like much but its enough to cause serious damage. The engine requires 91 plus octane to run optimally, make the appropriate power, and not destruct itself.

You must have an old BMW, because when you take it in for service they scan tool the system. If it shows timing is way jacked because the engine is trying to prevent knock they will check it and will void the entire warranty. I know this for a fact as I know a lady who walked down that path with them.
this right here...

OP look...

it's like if you're trying to keep a certain weight and not lose muscle... you start reducing your caloric intake and overtime you become smaller and weaker...

stop starving the car! :(

put 91 or 93 in it dude!
 

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68 Posts
I usually use Shell V Power...The other day (Im in New Jersey) I stopped at a SinGin Oil gas station and filled up with 93 ..The gas must be low quality or watered because I can feel a complete difference in the car..especially in boost..feels flat..Never going to that cheap brand GS ever again..I guess when it comes to fuel 93 at whoeverthe**** and 93 @ Shell,Hess or any other big name staions you really do get what you pay for..
There was a Delta station up in North Jersey that was recently accused of doing just that, watering it down to the point that many customer cars stopped running. I always used Hess or Shell too when I lived there too.
I'm in the SW now and use Costco but I sometimes wonder if their 91 is much different than others or if it's their buying system that allows it to have lower prices, just like their other products.
 

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122 Posts
I already ran half that gas out and filled up with 93 V Power..Here we dont pump our own gas, you have to watch the attendant..a few times when I had a Audi TT I asked for 93 and had to stop the pump because the idiot just started pumping regular..I wonder if this is what happened the other day..I didnt watch and the car felt like ****tttt...seems a little better now..
 

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I already ran half that gas out and filled up with 93 V Power..Here we dont pump our own gas, you have to watch the attendant..a few times when I had a Audi TT I asked for 93 and had to stop the pump because the idiot just started pumping regular..I wonder if this is what happened the other day..I didnt watch and the car felt like ****tttt...seems a little better now..
Same law applies here as well, I get out and watch the pump jockey rain or shine.
 

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2017 WRX
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19 Posts
I work for Subaru an for wrx an sti they will never recommend 87 octane, it even states in fuel door premium an on my online reference from Subaru itself. I just got done rebuilding a 2012 sti that had cheap gas in it an had to do what we call the “50k maintenance” for new block, of course was for #4 cylinder but cheap gas doesn’t help the situation.
 

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2016 WRX base
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8 Posts
Being the in process of acquiring a 2016 WRX (and no prior Subie experience), I d/l a copy of the 2016 OM and found the fuel reference. I wasn't really surprised that 91 Octane (or higher) is... suggested/recommended/whatever. The reference is found under fuel 'requirements' and talks about the fuel design requirements for the engine.

Apparently (at least from the 2016 OM), the STI is designed for 93 Octane but can use 91 Octane. The WRX is designed for 91 Octane and can use 87 Octane. Interestingly, the OM goes on to state that using 87 Octane will not cause engine damage or affect warranty.

From page 7-3 of the OM of the Except for STi cars section:
"
Regular unleaded gasoline with an octane
rating of 87 AKI (90 RON) or higher may
also be used. Using regular unleaded
gasoline will not be detrimental to engine
durability, nor will it affect your warranty
coverage. However, depending on your
driving habits and conditions, you may
notice a decrease in maximum engine
performance, fuel economy or slight en-
gine vibration or knocking. If you experi-
ence any of these conditions while using a
lower octane rated fuel, you may want to
return to using 91 AKI (95 RON) octane
rated fuel as soon as possible. Addition-
ally, if your vehicle knocks heavily or
persistently, the use of 91 AKI (95 RON)
or higher grade unleaded gasoline is
required."

I'm in NC and Costco here has 87 and 93 octane gas. 91 and up will be used in the WRX. The 3.8 V6 in the Genesis Coupe we just sold was designed for 87 octane. I guess the better fuel economy of the WRX will be offset by the higher fuel prices. Oh well. Small price to pay.
 

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2016 WRX base
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8 Posts
The direct injection of the fa20f is more forgiving in a way
I figured the ECU would sort out the fuel and engine timing. Does it not generally work that way? I haven't heard spark knock/pre-ignition in many years. It used to be common on carburated engines, back in the day. And maybe that's partly why engines didn't last as long then as they do now. ;)
 

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10,806 Posts
Knock is a huge issue on performance engines. Has been for years. In a port/throttle body injected system all of the air and fuel is pre mixed before, or as the air enters the cylinder. Direct injection doesn't have to worry about that and fuel can be injected in at multiple points in the cycle as needed.

However because of the higher compression that's common with them, knock can be much more dangerous and easier to cause.
 

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2016 WRX base
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8 Posts
Knock is a huge issue on performance engines. Has been for years. In a port/throttle body injected system all of the air and fuel is pre mixed before, or as the air enters the cylinder. Direct injection doesn't have to worry about that and fuel can be injected in at multiple points in the cycle as needed.

However because of the higher compression that's common with them, knock can be much more dangerous and easier to cause.
Good points. I expect a turbo engine might be more prone to pre-ignition damage than a NA engine too.

Has the Subaru DI had any issues with carbon buildup?
 
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