Well, it could be an issue if fuel dilution is present, ethanol wont really mix all that well with motor oil. They are both mostly polar molecules from what I understand. Only opposites attract.Do people who run E100 change their oil sooner or later than they would with gas? What is written on the owner's manuals of the cars sold in Brazil? Don't really understand why manufacturers say to cut OCI in half in the US when using E85 because to me it always seems like oil is in a better shape with E85. I just did two oil changes on cars that run just gas with OCIs similar to what i do and as always, the oil just feels more gritty between the fingers and more acid on the skin. Not very scientific but i'd like to understand why my real world experience is so consistently different than the common idea of "E85 destroys the oil, change twice as often just like your car's owner's manual tells you to".