I don't want to start any wars or anything, I just want to ask a question to people who know, or have the owners manuel for the older cars.
I seem to remember reading somewhere that the 84 and 85 500 engines required only 87 oct fuel. I don't remember where I read it or even when.
I have always used the best fuel I could find however, at this time money is tight, and gas prices are high. Yesterday, when I went to get gas, 93 oct was $1.76 and 87 was $1.56. So I says to myself, I'll give it a try. So I did. The car runs the same, no spark knock, starts good, idles smooth, etc.
I don't have an owners manuel for this car (why to people take the manuels out of the car and not return it?) so I would like for someone who has an 84 or 85 500 SEL to look in there manuel and see what it says.

Thanks

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84 500 SEL (307,xxx miles)