Originally Posted by wrxsti.l
Don't get me wrong, I am not saying E10 is a poor performer, I have had great results using it - I just wanted to point out it has quality issues and your tune should factor that in for engine longevity
5% min is what you want. 10% is too high and you are sacrificing a lot of your headroom and limiting your margin of safety.
On E10 I had around <2%, on straight pump I have <1% - and that is with non-standard larger injectors
It is all in the tune. Spend a little time on it and less than 5% is not that hard - even with inconsistencies in fuel quality.
You're right of course but it's tough when you travel a lot and are filling up at unknown stations. When I use the same station all the time I can keep it much closer to zero.