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Can ethanol harm my (old) car's engine?

I have a 1986 1/2 Toyota Supra; I use high test gas in it. Was my car engineered to accept alternate fuels? Can the ethanol so common in today’s fuel offerings hurt my little car’s engine and components?



RTM!(read the manual)

Your owner’s manual has this information. I am virtually positive that your car can handle up to 10% ethanol without problem.

The manual will also tell you if premium is required. If it’s not, stop wasting your money on it. Regular gas is expensive enough!

As NYBo said, if it does not call for premium and I tend to think it did not, using it will only make the oil companies richer and do nothing for your car. The only thing premium about it is the price. It happens to be higher octane, but octane does not measure power or mileage.

Nice car. How many miles on this gem?

There may or may not be anything in the owner’s manual about ethanol, as it was not used in pump gas in the 1980s. It’s hard to imagine there would be any damage using up to 10% ethanol, however, and since it’s getting harder and harder to find gasoline without ethanol, you don’t really have much choice. I wouldn’t worry too much about this.

As others have mentioned, you only need premium gas if your owner’s manual specifies it. Otherwise it’s a waste of money. If your car is turbo-charged you probably need it. $4.00 per gallon. Ouch.

You cannot use alternate fuels in this car. You probably can use 10% ethanol (E10), but it is not considered an alternate fuel. To me, alternate fuels are E85, propane, methane, or biodiesel. You can’t use them.

If you mean E10, you are probably OK. I doubt that your owner’s manual would address this. As a Toyota dealer if you are really concerned.

I had no problems running e10 in my 65 Malibu, so something 20 years newer should be able to handle it

The 10% ethanol blend common many places won’t damage your old fuel system. Where I live, they only do the blend part of the year and I’ve noticed I need to retune some of my older carbureted vehicles to get them to run smoothly on it, but your Supra’s fuel system is pretty similar to a modern one and will automatically compensate.

Another Supra owner. Neat. My '87 Supra non-turbo runs very well on 93 octane with 10% ethanol. It is not a problem. I’ve even run a mix of 93 and 89 octane on occasion with no problems. These cars were factory designed for 91 octane, and have a knock sensor to protect the engine from knocking and pinging. Just remember that using less than required fuel for extended periods will cause carbon build-up, and reduced fuel mileage.

Ethanol blends have been on the market for a very long time; a 5-10% blend should be OK in any car built in the last 20 years or so.