I wouldn't do it voluntarily but am just thinking about worst case scenario - stuck 400 miles from Calais and needing to get back for work etc. I wouldn't feel confident about doing it unless someone can provide the specifications of the two fuels for comparison.

It may be prudent to simply call off the trip but I thought I would explore alternatives.

Thanks for the quick replies, much appreciated.

I'm inclining to your and others view; if I was running an old diesel engined car it would work fine as they can cope with a wide variety of fuels (old chip fat etc.!) but it would be risky on a modern car.

The trouble is the dye stays in the tank for months. If Customs stop and test you within 6 months of using it, you may be caught .

(Not that I've ever been stoppped and tested ever in 20 years of driving diesels.

I am in Brittany just now and there are supplies of fuel about. Local supermarket had a delivery of petrol yesterday and judging by the long queues at another they also had fuel.

He needs space in the boot for the wine and other goodies.:)