I use powerservice cetane boost in the white bottle occasionally. A cetane booster makes the diesel fuel easier to ignite. This means the fuel starts burning sooner and it flattens out the pressure peak in the combustion cycle. This better approximates the ideal diesel cycle and improves efficiency. Using more cetane booster than is recommended is a waste as you can only reduce ignition time so much.

I also use a little ATF now and then in the tank as it cleans out the fuel system.

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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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