This biggest problem with ethanol comes when your car sits for a period of time. They were never really intended for enthanol in any amount to be used. It's been proven thru testing vehicles get worse fuel mileage with ethanol. And the EPA has suggested going from 10% to a 15% mix. It's bad enough that gas degrades over time ,attracting moisture especially, then you add in a component that inherently contains an amount of moisture. Exxon/Mobil is the first supplier that comes to mind that sells ethanol free premium. You have to think of how you treat the fuel for anything with a small engine (mowers,trimmers,generators). I use Stabil primarily but there are a couple others. It's sad I have and can't think of names at the moment.

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1983 300SD
1988 420SEL