I have the factory oil cooler on my bike. 2012 (FLHTK) I have always been aware that the hot air coming off the oil cooler is flowing under and up onto the voltage regulator. I don't think adding a fan to the oil cooler is going to help this any. All that hot air going onto a sensitive electronic control device can't be good. I upgraded my charging system to the HD high output alternator. This set up moves the voltage regulator up a bit and more out of the way of that hot air stream. I have also added the Wards fans to cool the heads. This being the hottest part of the engine it just made sense to me to cool them.