Well ATF in my fuel filter did something to my pump or injectors as my car has a smooth idle now, I don't think its a myth or a wives tale. Its not a placebo effect either. A friend commented that my car sounded smoother and asked me what I did.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

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