Dot 3 is really the only choice. You could use Dot 4, my recollection is it has a higher boil point. Not really an issue for most of us. Dot 5, silicone fluid....you'd need to do a full rebuild, replacing all the rubber seals and o-rings. Then if no moisture ever entered the (should be) sealed system, it'd be good for years, if not decades. But really, Dot 3 is the one.
RonR
