Do the answers on the 53 plate 2.8 LDV lpg switch also apply to a 51 plate ?

I have a smaller engine van but similar problem. Does the dual fuel always start frompetrol and then have to be switched to lpg and then sitched back when (or must it be before?) you turn off engine as otherwise it won't then start again?

And presumably you can always drive on petrol if you run out of lpg but not on lpg if you have no petrol as you cannot fire up - is that right?

Anyone know what the typical tank holds for petrol and lpg on a standard LDV Convoy Lwb van as I have no owner's handbook after recent purchase

Thanks

Mike Southampton