Will ethanol hurt my 2008 altima?

E85 or 85% Ethanol (highest amount of ethanol sold in large quantities in the United States) can hurt the performance of your motor if it is not specifically designed for it. The best way to tell is if your fuel cap is yellow. However, most gasoline sold in America is regulated at E10 or 10% ethanol and has been that way since 2008 (unless specifically designated rec fuel). Your factory fuel lines and injectors are able to withstand that amount of ethanol as it doesn't have a terribly large effect of the stoichiometric ratio at which it burns (i.e., E 10 Stoich AFR = 14.1 versus pure gasoline, which is around 14.7).