If you use DOT5 silicone fluid, make sure that the rubber components are compatible. Older rubber parts are made of a different rubber compound that reacts poorly with DOT5, it actually softens it, and in some cases, dissolves it. I know about that from personal experience.
I also would not call it "forever fluid". While it does not absorb moisture like the glycol based DOT3,4, and 5.1, it also doesn't disburse it in the system, either. condenced moisture in a system with DOT5 has a tendacy to pool in the lowest points of the system, as it doesn't mix with the fluid and DOT5 is lighter than water. Annual flushing is still suggested.
