10% ethanol gas

[D_Eclipse9916]

It will improve the knock rating, however, it wil reduce gas mileage as your car will require more ethanol than gasoline. The reason a carbeurated engine may be having problem is it does not read and put in more according to the o2 sensor (even with ethanol, stoich ratio is different but the computer does it right) However without an engine management your car may not be getting enough gas in that it needs causing it to run lean with a different mixture with ethanol.