If you google this, you will see all sorts of horror stories, mainly from outfits with the vested interest of making as much money as they can out of this. I even read of the risk of an engine 'exploding'!!

At 50:50 the fuel would still have been pretty oily. In such a short time I doubt if any significant damage has been done to the fuel pump and injectors. Bog standard engines, especially diesels, are pretty tough, so it should have survived a few stresses/jinking caused by pre-ignition (used to be called pinking!). If I couldn't have syphoned/drained some off, I would have just brimmed it, driven another 100 gentle miles, brimmed it again - and so on. Even if having to buy some expensive new bits, the cost would probably be less than the costs (plus the hassle) of changing the car. Looking on the bright side, it might even run better if it's an old car - it used to be (unofficially!) advised to add up to around 15% petrol to clean dirty old injectors.

I wouldn't worry about it too much, they use petrol (gasoline) to thin the diesel out in the parts of USA that get extreme cold during winter. Add some two synthetic 2 stroke- oil, about 2% for about a couple of tankfuls, it doesn't make ash when it is burnt, lubricates the high pressure pump and injectors.

Edited by focussed on 14/08/2018 at 14:42