Hi,We have a 1999 Citroen Xantia HDi Engine and we are thinking of using Biodiesel instead of diesel. I have just read somewhere that it is ok for older engines but not HDi engines.I am a bit confused as I read somewhere else that it is ok in all diesel engines.Does anyone have any info on it or has anyone tried it in their HDi engine,Would be grateful for any info.Many Thanks.Lynn.