Might be worth sealing up the leaf trap under the bonnet scuttle. The foam there perishes and when it rains, it tends to go down that hole onto the poor fan.
Against my will, I ended up sealing mine with some clear silicone to stop rainwater getting into the fan.
BTW, remember, once its greased, let it settle for a day or two, then close all the vents apart from 1 and put the fan on full speed with a cloth over the *only* open vent. Otherwise, you'll end up with grease all over your car!