After running nothing but regular I treated my car to 5 gal. of chevron supreme today. I could tell the difference almost immedialty. with the engine at operating temp. flooring it first gear you can start to hear the rear tire break loose and then chirp into second. my tired old stock slant never did that with regular. ( and I tried believe me I tried) it also idled smoother.

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64' Valiant Signet 5.9, 64' Dart 170 moredoor 3.7, 67' A100 3.7, 00' Dakota SLT 4.7

It's all in the mind. There is no means by which your engine could be more powerful or smoother on premium gasoline than on regular. Modern computer-controlled engines that are designed for premium but run on regular, yes, but not your slant--6. Premium fuel does not contain more energy, and the energy it contains is not more available.

The power of suggestion is much stronger than we like to believe.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

What kind of compression ratio does the engine have? Unless the regular you've been buying is somehow bad (maybe they're sneaking in alcohol which would have a lower energy content?) the difference between regular and premium is that the premium, in non-buzzword terms, is less explosive, a quality needed for high compression.

Chevron gas is superior to other gas companies. I was tangetially involved in a lawsuit from a Chevron staion owner against Chevron and got to read some of the documents about what chemicals and treatments Chevron adds to its gas. It is better than yoru average gas, but I wouldn't worry about it for a slant.

I hadn't thought about this until I read this post, but when I bought my '71 slant a few weeks ago someone told me that I might have to add a leaded additive to the tank since it was born to run on leaded gas... what is the deal - is there truth to this or am I fine just pumping 87 into it?

I know this is a silly newb question, but... my first old car. you guys are great.

Hardened seats didn't come on the slant (and all Chrysler engines) untill 1972. I personally wouldn't worry about running unleaded, unless you do some towing or alot of high speed driving.

Read my article here; no need to add anything. Your engine will live a long and happy life on no-lead regular gas.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.