I have a similar setup on the Petter, using a 12 volt car radiator fan connected to the 12 volt outlet of the alternator. Like yours, the fan neatly comes on automagically only when the engine is running. Another chap on here suggested having temeprature sensors to switch it on and off according to demand, a good idea, but in my case they were off most of the time, so didnt really warrant the extra complication. So, to simplify it, I just put a car ballast resistor in series, the fan just idles along full time. What I may do with this one is to add some way of heating the lubricating oil. These Listers are dirty in the sump, and I reckon its because the oil never gets hot enough to boil off the contaminants, thereby forming sludge very quickly. Extending the pump outlet oil line to a few turns around the hot exhaust may be all that is needed, I think it would help. But then, Listers in general dont seem to mind shitty oil, and Ive seen some really bad examples where the oil is the consistency of thick cream with coagulated lumps. an emulsion of oil and water, but the bearings show no signs of distress at all. So, I could be over thinking it.