I'll also recommend the block heater rather than the oil heater but you'll just have to pick your poison. Chrysler used to sell block heaters over the counter, not sure if they still do or not. Fairly nice little heater that goes into the frost plug on the side of the block and then has a cord that is long enough to run out the front under the radiator. I installed those on my '76 D200 truck since otherwise I couldn't get it started on cold mornings. With the block warm it would take right off. Without any heat it would just crank and crank until the batt was dead.