I used Power Service in my first diesel, an awful 1986 Ford. I have since had a 94, 98 and 03 Dodge. I have used absolutely nothing in any of them and had no problems with gelling. I find that the fuel is better than it used to be as far as gelling an water content. Years ago, I used to have problems with fuel gelling and when that happens, it will leave you there. This is just my experience, others may differ in their opinion. I would probably use a conditioner if I lived in Alaska, Canada, or the Northern Great Plains.
Dean