@davidoft1 I think we must have interpreted this differently. When the OP said "Add flushing & run till warm...
Drop it all out....
Without the drain plug pour 10 litres of diesel through....
"
I read it that the last thing put in was diesel, and I think you must have missed that part, and just seen the flushing oil part? Then going on to something about 50 years ago that I didn't really get. Anyway, my point was that would still leave a little diesel sitting where semi-synthetic engine oil used to be, and that is worse than just changing the oil!
Ok, I think that's clear. He's not using diesel now. Phew!
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