Heat and dust are the enemy of Piston boots. In general, the heat comes from the pads into the caliper through the pad backing plates which then melts the boots. An indication of heat can be that the red paint can darken and turn red-brown or burgandy in color. Brembo calipers are sometimes called brownbos because of a color change.
Fluid has little to no impact pn the cause. Icy pedal or a pulsing feel when hot is an indication of boiling fluid and a better fluid will reduce or eliminate the boiling, but the heat contributes to boot failure regardless of the fluid boiling or not.
Best way to prevent the issue in the future is to keep the calipers cool. Add/increase air flow on the brakes via better ducting, changing to GT4 front fender liners, titanium shims, better pads and better cooling rotors. Larger rotors help, too. Stopping force is in ft-lbs and the further from the axle the center of the pads are, the same stopping force is maintaned with less pressure on the pads, causing less heat to be generated. That is in addition to the increased stopping capacity of larger rotors. A Type 5 Titanium Vanadium Aluminum allow brake shims fit between the pad backs and the pistons. The proper alloy shim has 1/2 the heat transfer capability of the steel pad backs and helps keep heat off the caliper pistons.
I have Brembo GT brakes on my Cayman with 380mm front rotors and 345mm rotors in the rear. They offer a racing version (GT-R) with the same rotors but with calipers with titanium seals to eliminate the rubber melting problem. Double the price. On my car, I've had issues with the rear brakes overheating, but adding 997 GT3 air ducts and improving driving has eliminated the overheat problems for me.
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