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Flex Fuel/ e85 Guys, Additives?

3553 Views 2 Replies 3 Participants Last post by  EJ257
I just ordered the Cobb Flex Fuel Kit for my '15 STi, I've researched the fuel plenty before so I know what I'm getting into ( Gobs of TQ and low detonation, that's what I'm getting into!!) anyway, but buddy with a GTR informed me that if you run E85 a lot, build up can occur and cause the injectors to gum up.

Do any of you guys use an additive? In the GTR community Star Tron is very popular ( and in the 15+ WRX community Lucas Ethanol conditioner is popular as it lubricates the HFPF and makes a failure less likely.

I've also been told that since I'll be running Flex Fuel, as long as I run a tank of 93 Oct every few tanks, I won't need any additives whatsoever, as 93 contains detergents and lubricants.

Any insight?
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I've been looking into this as well. From what I've found (on YouTube) some folks use conditioners and others run 91/93 oct every few tanks.

I'm thinking about going E45 first when I make the switch.
It really depends on how you drive your vehicle.

When I was DDing the Subaru and I had a 55-60 mile RT commute, 90% Interstate, I hardly ever saw enough boost to make the EWG open up (let-alone full power). I could go an entire work week and not hear it once; I don't need E85 for that. There were other weeks where the weather was nice and I would do some fun driving up in the hills during the week, in which E85 would've been nice. On weekends, I'd likely want to run E85, and then on Sunday, I'd probably top off with pump fuel again.

My thoughts are to have an idea what your driving for that tank will be and make a game time decision which fuel to use; just make sure to choose pump gas once in a while. The joy of flex-fuel (vs reflashing based on fuel type) is that if you get a phone call from a buddy who wants to go out driving after work and you're still half-full on pump gas, you can fill up the remainder with E85 and let the blending tables do their thing.
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