Dexron III is what you should use. First and foremost change the filter. One of those $100 presure flush services isn't a bad idea either.

I have no idea how well the synthetics work out, I don't know what it is suppose to get you other than costing you more. I have never seen an independent test comparing it to anything.

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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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