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91 or 87 octane?

10K views 6 replies 6 participants last post by  AWDFTW 
#1 ·
on a 2016 2.5 Outback Premium, any advantage to switching to 91 octane over 87?
 
#4 ·
From what I remember, Amoco Gold used to have some special detergents in it that the Silver and 87 did not have. It was my understanding that a tank or two of that per year would help clean the fuel system. I used to use it in my '74 Roadrunner and could tell a difference not only on that tank, but also the following tanks.

I have toyed with the idea of running a tankful of non-ethanol fuel through the system every other month or so to alleviate any water/fuel issues associated with E-85. Any thoughts from the group regarding that practice?
 
#6 ·
If you want to clean the fuel system Top Tier gas or Techron additive are good choices.
The engines on my power boat have very small idle circuits. Every year at spring commissioning one of the idle circuits will be plugged. The only thing that reliably cleans it quickly is Techron Concentrate.
I hold the engine at idle speed for ~5 minutes to get the TC through the carburetor then let it sit for a day. Next day at start up it may sputter for a second or two but that's it. I've tried other products and tactics without such good results.
 
#7 ·
There are tons of threads and info on this.

Short answer, no need.
 
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