Went to a local hydraulics guy who made custom seals. I got a spare (rare custom made from Brad) and this guy could do the same as the people in Sydney (iirc) who made the ones Brad had.
The guy said that the various rubber compounds available were not always compatible with different brake fluid compositions from the various fluid mfrs. Some brake fluids ate some rubber compounds more than others and there was evidence of rubber degradation from certain chemicals in the some brand fluids. That's all he would say.
My guess is it may depend on the fluid you use and the compound of rubber used in particular batches of seals from the oem supplier. You won't know according to this guy until the seals fail early and inexplicably. It may be hard to know if there was another less obvious cause besides a buggered thrust bearing or rotten fluid.
He said that he could have a seal made that would stand up to current known chemicals in brake fluid, but he would give no guarantee. Food for thought.
My concern would be that NOS of oem slave cylinders and NOS of rebuild kits may not be compatible with the stuff in the latest brake fluid, if this guy is to be believed. I 'spose you could be lucky or unlucky. My old model type slave cylinder is still going, touch wood, but I would gamble on the rebuild kits for the old type if they were cheap enough.
