Because of air quality in my area all gasoline sold must be an ethenol blend (up to 10%). I have a 1996 and a 1999 Saturn SL, the 1999 runs OK with the blend, the 1996 has runs less well with the blend when it is hot & humid or when the air conditioner is on. I am however experiencing lower mpgs and less power with the blend. Does the ethenol lower the octane of the blend? (I use 87 per the owner’s manual. If it does, would using 89 octane blend raise the octane level to pre-ethenol blend levels?

No, the blend should have the same octane as the lable on the pump. You will get slightly less mpgs (3%, some report up to 10%). As for poor running, the E10 may be making a weak fuel pump problem worse in your '96. You might get that checked. You could alway put in a tank of premium, see if the problems go away.

My '96 Subaru and my '97 Acura run just as well on E10 as they do on regular gas, but both get reduced fuel mileage with the ethanol blend. The reduction is about 10%.

If all of the gas in your area is E10, how do you know it’s the fuel that’s causing problems with your '96 Saturn? It could be something else.

87 octane is 87 octane, regardless of the blend.

What texases said (though I suspect a tank of premium won’t do a thing).

I was just going to mention that the 10% E is not local to your area. It is pretty much everywhere. And it has nothing really to do with air quality. It has a lot to do with a) a misguided attempt to increase domestic fuel production AND/OR b) a powerful agricultural lobby that continually finds new “uses” for overproduced corn.

Your car is designed to run on up to 10% ethanol. You must have some other issue if it’s not running right.

I have a 93 Chevrolet Caprice that had a slight ping with regular gas and no ping with mid-grade. When NJ went to E10 year round the Caprice took a hit with mpg, but no longer pinged running on regular (87 Octane) E10. The problem with the 96 may lie elsewhere.

Ed B.

Is the octane rating from the base fuel or from the blend? Ethanol has an octane of 130. If blended with 87 octane gasoline the result would be an increase in octane. A 10% ethanol blend would result in 91 octane, 15% ethanol, 93 octane and 29% ethanol 95 octane. But the ethanol has significantly lower BTUs and even if compression ratios are increased to maximize the higher octane MPG would never approach that of gasoline.

I don’t know, but I would think that they would sell no higher octane than the label on the pump. It would be a waste of money (on their part) if they did otherwise.

Thanks for the input. I had been using a “no ethenol” brand gas purchased in another county where the so called air quality didn’t require ethenol. Gar ran very well, I noticed the change when I went to ethenol blend where I live. I can live with the hot& humid and the air conditioner, the annoying part is the reduction in mpgs. When the 96 was fed the non ethenol gas, I could pull +(-)42 mpgs during highway driving (at a steady 60), the car is a manual 5 speed and I drive from the tach. Now I pull +(-) 36 mpgs with the same driving style.