Power Steering Fluid on 2001 Buick LeSabre

Can power steering fluid "evaporate" over time if not topped off regularly? Two Buick dealers offered different opinions. One said that the only way the power steering resevoir could go dry was for a leak to be present, that the fluid itself was like transmission fluid, viscuous, and cannot evaporate. The second dealer said that the fluid in my pump had evaporated, with no sign of a leak, which caused the power steering on my vehicle to fail and the pump to be replaced. Your opinions?

Asked by for the 2001 Buick LeSabre
The first person was correct, steering fluid will not just evaporate! The steering system is a "sealed system", it does not burn oil like an engine , it should not require frequent topping up. There has to be a leak.
1 answer