I have two 1980 300 TDs. On page 85 of the owners manuals it recommends blending up to 50% kerosene or up to 30% regular unleaded gasoline in very cold weather if #1 diesel fuel is not available. It says not to blend anything with #1 diesel fuel.
I have been running these cars on 90% settled and filtered WVO and 10% RUG for a couple of years.. Sometimes 100% WVO. This is in central California, mild climate. Steve