Habanero,

The 300SDL has a Om603.xxx engine.

The 603 engine has a fuel heater built in. It circulates the fuel thru the cylinder head but only when the fuel is cold. There is a thermostat that sends the fuel to the head when cold. When the fuel is warm, the thermostat allows the fuel to go directly to the secondary fuel pump, thus avoiding going thru the head.

If you are going to use WVO, you might modify the thermostat so the fuel always goes thru the head to be warmed.

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