Heat and age is more of a killer. I'd suggest increased fluid change intervals. If the pump is contaminating the fluid that bad it needs to be replaced. Also running a cooler does alot of good.
Speaking of heat, does anyone actually know what temperatures those things are supposed to run at? I shot mine yesterday with the IR gun, I got this:
1) high-pressure discharge port at pump = 120-125F
2) high-pressure inlet port at hydroboost = same
3) high-pressure discharge port at hydroboost = same
4) low-pressure return line from hydroboost = 90F or so, ambient temperature of the entire hydroboost unit really
5) low-pressure external reservoir (it's between the hydro and the pump, just another Chevy part

) eventually got up to slightly above 100F even tho the hydroboost actually returns very little fluid.
The lines at the steering box I didn't shoot at cause they're hidden by my air intake ducting and crawling under the truck or into the fender well just didn;t sound too appealing at the time...