To modify a modern automobile diesel engine into an aviation one cost thielert (and austro engines) quite a high amount of money. I think the amount cited for thielert was a high dual figure amount of millions Euro. Most of that went into fixing the lubricity problem and aviation grade engine management.
Modern diesel engines reach pressures up to 29.000 psi in their injection systems and the pumps to reach that do react to changed lubricity of course.
Old-Fashioned low tech diesel engine as you might find still in high number in undeveloped areas of this earth were indeed very tolerant to a wide range of differing diesel fuels.