Regular fuel + E85 VS Hi-Octane (premium) fuel.

Eddy Cruze said:

From the manual courtesy of Nick!
"However, E85 (85% ethanol) and
other fuels containing more than
15% ethanol must not be used in
vehicles that were not designed
for those fuels."


Why not try a gallon of Sunoco Racing fuel or "Sunoco 100"

Sunoco SS 100 is an unleaded high octane gasoline that is street-legal in California. Its 100 octane rating will allow increased boost levels in supercharged or turbocharged applications compared to premium pump gas. Sunoco SS 100 can be used in high performance vehicles both old and new.

Click to expand...

chevrasaki said:

My personal recommendation would be to fuel the car with 91+ octane.

As you've noticed the Cruze computers are sensitive to knock and will retard engine timing to protect itself if it senses pre-detonation. Knock is caused by the fuel exploding too early in the cylinder due to high temperatures, and high pressures. Since the Cruze is turbo charged, it's a check mark for high pressure. The intake temperatures vary wildly depending on conditions. But basically you're going to reach high temps at least a few times each tank of fuel. The exception is in winter when the temps are always cold.

I've toyed around with various grades of fuel and have settled on 93. I get better fuel economy with premium, which is almost enough to completely offset the price increase. Also, when I run 87 my car is very quick to pull timing and as a result it feels very under powered. Just feed it premium. It's not like it chugs gas. A car is generally your second biggest purchase, no sense in fooling around with mixing fuels it's not recommended to run just to save a few dollars. If you really want to save money on fuel, buy a 50cc scooter on craigslist, they get 110+ mpg and I wouldn't feel the least bit bad for filling it with 87 octane. Or bicycles I hear are an option for some people. Much cheaper.

Click to expand...

ProDigit said:

I don't think adding 2 gal of E85 fuel will cause any major damage to the engine, especially if you ride it off pretty frequently (fuel up at least once a week).
Regular gasoline already has UP TO 10% of corn juice in it.
And from my experience here in SoFlo, Marathon is closer to the 10%, while Shell is closer to 2%.

As long as the concentration is not too high, it shouldn't do too much damage.
What causes most damage, is water getting in the fuel tanks, 'drowning' the engine with non-combustible fluids, that work best on a hot engine.

Click to expand...

chevrasaki said:

Brace yourself, this could get boring.

It may take a few tanks to get the full benefits of a highly knock resistant fuel like 93. The car has knock sensors and will "pull" or retard the timing on the engine if it senses knock (aka pinging or predetonation). Knock happens when you put the air/fuel mix in a condition where it spontaneously combusts before the spark plug gets a chance to ignite it at the optimal time. When the air/fuel detonates too early, it can harm the engine. The cruze has timing tables for fuel as low as 87 octane so you can safely run cheap gas but there are side effects. The 1.4L engine in the Cruze is turbo charged so the air pressure going into the cylinder is higher than naturally aspirated cars. When you increase pressure of a gas, the temperature increases. Some of that extra heat is removed by the intercooler. But since the intercooler is sandwiched in between the coolant radiator and the A/C radiator, it will often heat soak in the summer, in traffic, or with A/C use. That's when the air intake temps skyrocket and cause knock, so the computer retards timing to protect itself which results in decreased power. Not a huge deal, but since the Cruze is heavy, and doesn't have a lot of power to begin with, now it has to use more fuel hence the decreased economy. Depending on how you drive, you may not notice it. But if you have a lead foot, you'll lose a pretty significant amount of MPGs running 87.

You can kind of get away with running 89 or 87 in the winter because the intake temps stay low. When air is cold, it's dense and more potent. Usually that means you can get more power, but the Cruze is torque limited so it uses the boost levels to control how much torque it makes. Since it can easily achieve the 148 ft-lbs in the winter with that delicious dense cold air, it doesn't need as much boost so the pressure is lower, which means the temps are lower, and since the winter air is already a lot colder, the air fuel/mix is a lot less likely to pre-detonate so the computer doesn't need to retard the timing. You'll still get less fuel economy in the winter no matter which grade you run because they have to blend in extra chemicals to keep the fuel from freezing, and it also takes the car a lot longer to reach operating temperature so it runs rich more often in winter.

Hope this helps.

Click to expand...