After my clutch worries a week or so ago I changed the fuel filter and the symptoms seemed to fade away and all was a well as my 1.9 cube van ever is.

Yesterday I had to drive 300 miles (return trip) to Warwickshire.

On the way I put £40 in the tank, which was low, and carried on. Very soon the symptoms returned...power loss and the feel of a clutch not quite transfering the power. It was worrying to be so far away from home and think that the van was about to fail. But I carried on and arrived at my destination.

On the way home I stopped to top up and it was a Shell garage and it was their optimax fuel. Back in the van, a few miles on there was a surge almost and the van responded and drove as normal. No more sluggishness. I remembered then that the £40 top-up had been bio fuel and began to wonder.

Could it be bio diesel that causes the problem?

pretty much all pump derv in the uk is about 30% biofuel now and it has been for a few years