I believe you can run heating oil as long as your fuel filters are good, and you will need to change them a bit more frequently due to a little poorer refinement. As long as you stay on top of that you should be ok. A guy I know used to siphon heating oil out of his parents home furnace tank for quite some time with no ill effects.

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Bart
1987 300SDL-T
1985 190E 2.3-16
1984 280GE Cabrio
1978 240D
1957 220S(running one day, I hope!)