Have done the same thing, although was only the one tank full. Maybe transfer half from the Transit tank and top up with petrol a couple of times. Small amount of diesel didn't make any difference to my running in short-term.
Oldjets
See my post:
Put diesel in my petrol tank - dont panic!
Postby Oldjets » 17 Jan 2011, 11:03
Had a slight senior moment at weekend while filling up and put a six litres of diesel in the petrol tank of my 1.9DG before I realised what I was doing.
After a slight panic, I filled on up with petrol, reasoning that in a full tank, the diesel would be well diluted down. I was also hoping that the rugged, simple design of my trusty DG would be able to cope with a slightly dodgy fuel mix much better than a modern engine with its fuel injection and lots of sensitive electronics. I'm pleased to report that it did! Did a 80 mile loaded run straight away, taking it easy for the first few miles, but then just driving as normal on A roads at around 45-55. I couldn't detect any difference in the way the van was running, no hesitation, misfiring or lack of power.
Just thought I mention it, in case someone else does the same - no need to call the AA out or drain the tank - seems a little bit of the wrong fuel shouldn't be a problem.
Oldjets