I only blew a cylinder head off.............!

I suspect, very strongly, that any self-destructing petrol engines following a diesel fill will either be coincidence, or peeps driving with foot t'floor (and even then it shouldn't happen...)

GJ, your car had the best part of 2 galls of petrol in it to start with. Adding the diesel brought it up to around a half-tank - twoandahalf galls or a bit over. And then you brimmed the tank with additional petrol. Man, you ain't got noooo problems there.

What to do now? Well, you could continue to drive it as it is until empty and then get back to 100% petrol, or you could keep 'brimming' it, say when the tank is down to threequartersfull. I wouldn't lose sleep over deciding between these two, but my understanding is that the latter is the better of the two options; if you drive it as it is until the tank is empty, then you are subjecting your car to the higher concentration of diesel for longer, so my thoughts are to keep diluting the mix by brimming.

But, don't lose sleep over it.

If you are at all concerned, then syphon out the tank - or disconnect the fuel line as it feeds the pump - and drain off as much as possible before brimming again.

But I personally wouldn't bother.

well i was going to go with what Ken suggested, just using the 60/40 mix i had to begin with and then fill it up all the way from fresh, however she'd not been running too badly untill last night, she was down to an "indicated" just above half a tank and decided she wasnt going to run all that well, got very smokey and lacked power alot more than before, more like how she was running when i first put the diesel in, so i topped her up again today and she's back to running better again! although the next refill might have to wait untill the week, if i can let the fuel level get lower and she still runs ok then i will, as i'd rather have more fresh unleaded in there than the mix of the two!

i'm guessing now that she's been filled up for a 2nd time since the diesel, the diesel mix itself will already be more diluted and less concentrated than before, so she might still run ok with less fuel in the tank? i hope so anyway!

The smoke will be the diesel
If its running rough pop the plugs put and clean 'em

she's due a service and some new plugs soon anyway!