Data seems to imply that the diesel engine lifecycle cost is slightly better now than conventional engines, so electing for a diesel replacement instead of a conventional engine overhaul can make sense... but it's a razor thin difference.
If you made leaded fuels more expensive-- more airfields are going to want to move to UL94, and more people at overhaul time are going to go the diesel path, and the problem will gradually get better.
Data seems to imply that the diesel engine lifecycle cost is slightly better now than conventional engines, so electing for a diesel replacement instead of a conventional engine overhaul can make sense... but it's a razor thin difference.
If you made leaded fuels more expensive-- more airfields are going to want to move to UL94, and more people at overhaul time are going to go the diesel path, and the problem will gradually get better.