I can vouch for that statement, I tried and got codes. I've blended e22.5 before with no problems. But e35 gave me P0191 and P2177.

 

I have it on good authority that even E15 is hazardous to a non-Flexfuel fuel pump. Apparently the blend become more corrosive very quickly after 10%.

 

You might cringe then when I tell you that during my diagnosing and troubleshooting before learning that my problem was the injectors not being the HHR injectors and I was chasing my Alcohol Fuel Percentage problem I ran 2 full tanks of E85 through the Cobalt engine in my HHR and it actually ran great with more power and smoother! I would have kept doing it too if the pump with E85 wasn't so far out of my way. But since my fuel system is HHR Flex Fuel and other than the injectors being cobalt at the time...I don't see anything wrong with putting E85 in it now especially since I now have the HHR injectors in there...
Whats your concern with it?

 

Your ECM is for FlexFuel. I have been trying to tell you that from the start. There are other things like seals that are different, mostly the programming. The ECM is the reason the alcohol wasn't right, it is programmed to adjust for varying amounts, a non flexfuel ECM is not. They interpret O2 differently.

I think I explained the concern if you read in context.. The O2 sensor senses the Oxygen content of the exhaust, then send that data to the ECM. If the ECM is programmed to account for E85 it will. The engine needs to be designed for the corrosive properties of alcohol.
It is a SYSTEM, you can't change just one parameter and expect everything to work the same.

I am expecting your problems to return after a time without reflashing the ECM.

 

So after the fuel passes through the injectors (Which from fuel tank to injector is all Flex Fuel ready) it is sprayed onto the back of the valves and drawn into the combustion chamber of the cylinders... what your saying is that it is possible that GM engineered the valve seals and valve stem seals differently to resist the alcohol, ok I would agree too. I don't plan on running it all the time or anytime if I can avoid it. Only for fun
Donbrew: your comment about expecting my problems to comeback over time... is that just if I run E85? Do you still expect my problems to come back if only running regular pump gas?