Does buying gas that has alcohol in it harm your car’s engine?
On newer cars and as long as it’s E10 gasoline, no. But you can’t use E85 gasoline in an engine unless it’s a Flex-Fuel vehicle.
It isn’t the greatest thing but usually there aren’t any problems unless you are storing the car for a couple of months. Then, fuel stabilizer will help. Sta-Bil (or whatever it’s called) is sold at Wal-Mart and other places. There was talk that you could cause an explosive effect if you add drygas to the mix when the alcohol breaks down and causes water in the gas but I don’t know the specifics of that.
All newer cars are fine with E-10 or less. E-10 is 10% alcohol. E-85 is only for specially designed cars identified as Flex-Fuel. Alcohol has less energy per unit of volume so it will give you slightly less mileage, all else being equal (which it never is).
NJ mandated E-10 year round a few years ago. Other than a 5-10% decrease in mpg, I have not had any problems in either my 93 Caprice (74k) and 2000 Blazer (101k). I’ve had the vehicles 7 and 6 years respectively. In fact, since I’ve been using E-10, the Caprice no longer pings in the summer with the AC running. I used to have to alternate fill ups between regular and plus to control the pinging.
The Owner’s manual for the Caprice states that E-10 gas should not cause any problems. I suggest you check the Owner’s manual for your vehicle.