Use GM Power Steering Fluid no. 1050017 or equivalent.
See Figures 1, 2, 3 and 4
The power steering fluid should be checked at least every 6 months. Power steering fluid level is indicated either by marks on a see-through fluid reservoir or by marks on a fluid level indicator on the reservoir cap. There is a Cold and a Hot mark on the dipstick. To prevent possible overfilling, check the fluid level only when the fluid has warmed to operating temperatures and the engine is shut OFF . If necessary, add fluid to the power steering pump reservoir.