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What Octane Fuel to Use? (2002 Twin Turbo B4)


GangrenousGraps
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Have been using 98 Octane due to believing this is what was best for the TT legacies.

Due to skyrocketing fuel prices, I am wondering if this truly is required, or if 95 or 100 octane fuel (both of which are cheaper than 98) will work just as well?

 

Thank you very much :)

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Not 100% on the twin turbo B4 legacys but the sequential turbo B4's (GT's) are tuned for 100 octane in Japan. Subaru's are notorious for knocking or ticking from detonation when people regularly put 91 octane in their car. I use 95 because it's only what's available where I live and put octane boosters in every 3rd time I fill. Hope this helps

Sent from my SM-G980F using Tapatalk

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I don't know why on earth you guys are suggesting 98? He's clearly said 100 octane is available and it's cheaper..... 
Do you guys read?

So yes, 100 octane man. I can also attest that in a twin turbo legacy, just going from 98 to 100 octane got rid of a slight detonation problem I was having. 

 

Definitely not 95. 

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next question did anyone ever verify the "Ethanol is bad for your fuel lines" warnings?

 

I understand from a quick google that's where the extra 2 RON's are coming from? 

 

:P (I'm always learning)

  

On 17/01/2019 at 1:28 PM, boon said:

EDIT: I am dumb. This is what Subaru NZ said about it roughly 18 months ago:

 

Ethanol suitability for Subarus

Most Subarus purchased new in New Zealand since 1990 are capable of running on the ethanol blended fuel now being introduced to the local market.

However any Japanese domestic specification models which have been imported here second hand (i.e.). second hand Japanese imports - should not be run on the ethanol blended fuel.

These cars are only suitable for 3 percent blended fuels. The fuel being sold in New Zealand has a 10 percent ethanol blend.

The 10 percent ethanol blended fuel could cause damage to the fuel line, fuel injector sealing, fuel pump or fuel regulator of these second hand Japanese imports. The fumes from the blended fuel after combustion can also have a harmful effect on the catalytic converter, the exhaust gas regulator and the muffler.

Those Subarus which can use the 10 percent ethanol blended fuel have a 17 digit VIN number beginning with either JF1 or JF2. The VIN number can be found at the bottom of the central door pillar on the passenger’s side of the car or in the engine bay.

The second hand Japanese imports which should not use the ethanol blended fuel have VIN numbers starting with 7A8.

A small number of models sold new in New Zealand cannot use the 10 percent blended fuel. They are.-

Legacy RS, Legacy GT, Legacy GTB, Legacy RSK and Legacy Blitzen from 1990 onwards; the Impreza STI from 1997 onwards and the Forester STI. They do not have JF1 or JF2 VIN numbers.

Owners who are not sure if they can use the ethanol-blended fuel in their car should consult their nearest Subaru Authorised Dealer.

In Summary

DO NOT USE Ethanol Blended Fuel - E5 or E10 if your car is:

 

  • A Subaru with VIN Number that starts with 7A8, or
  • Second hand Japanese imported Subaru, or
  • A New Zealand New Subaru that is any of these models:

  • Legacy RS, Legacy GT, Legacy GTB, Legacy RSK and Legacy Blitzen

  • Impreza STI

  • Forester STI

 

 

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4 hours ago, Joker said:

next question did anyone ever verify the "Ethanol is bad for your fuel lines" warnings?

 

I understand from a quick google that's where the extra 2 RON's are coming from? 

 

:P (I'm always learning)

  

 

 

NPD 100+ Fuel is advertised as ethanol free so it seems as if this is the best option for me :)

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4 hours ago, newsuba said:

NPD is ethanol free but to get that 100 they use additives in greater than the recommended dosage.

 

This was covered months/years (?) ago when NPD 100 was first introduced and discussed.

 

he's right you know (from 2018)

 

  

On 1/11/2018 at 1:47 PM, Loren said:

Unless tuned to take advantage of the higher knock resistance, you are running a fuel that is less willing to burn and might have less energy than BP98.

 

If you have a Jap spec ecu that was tuned to 100 octane... then awesome.

 

was a fun wee search

 

from the same thread

 

  

On 29/10/2018 at 11:35 PM, GC8E2DD said:

 

and

 

  

On 6/09/2019 at 10:23 PM, SpeedySub said:

I have been running my 3.0 Outback for the last week.

I try to usually run 98, but most times its a blend of 98 and 95 depending where I am when I need to refuel. 

This week I have driven just over 500kms mostly around town and at a couple of times on a short trip down the motorway and a few 80km roads.

With the NPD 100+  the car is running about .5km/l better fuel consumption, could be better if more highway/motorway driving was done.

The engine definitely runs smoother and has picked up some pep at lower revs, also it runs about 1 notch cooler on the temp gauge.

 

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14 hours ago, thewabbit1 said:

 

Late to this, but ~283 for 100 at NPD Wigram today, ~330 for 98 at BP Moorehouse on Friday and BP Hoon Hay today

 

Yeah same as here in Nelson be $4 for BP98 soon at this rate 

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I bike to work every day (or work from home) and only drive to the gym once or twice a week (have a setup at home as well). Weekends I'll drive a bit more.

Previously i'd fill up a full tank every 5-6 weeks. Now i'm topping up most weekends. Put ~7l in on Sunday - saves having a $200+ hit every month or so

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