different power steering fluid with SLS?

[StephenVA]

What was in there BEFORE you dumped more of something in?
RED = ATF (Brown is old ATF)
Green = CHF-11

[StephenVA]

Updated DIY for the correct 540 application the OP owns

The flush process is pull off the line from the pump to the reservoir (RETURN LINE) and stick it in a gal pail/container. top off the reservoir with the correct fluid (ATF or CHF-11) and start the car. With a competent helper turn the wheel L/R lock to lock while keeping the fluid level at more than 60% full, slow is better. No need to race the engine, idle will do it all. If required you can add in a extension to the line with Home Deport brass hose union of the same size to make it easier to reach the collection bucket. Flush the system with approx 2.0 Qts which should be enough to clean and refill the system.

Install the new lines and new Reservoir, use the pinch type of clamps, top off with fluid, start check for leaks, turn wheel lock to lock 5-6 times, Top off to correct level, road test, recheck for leaks and enjoy the greater road feel and reduced noise levels from the P/S system. NOTE: Replace the little rubber bumpers under the reservoir mount points if torn/ripped/missing.

TIPS: When removing the bolt from the cooler make sure you use WD-40 on the bolt and mount, loosing it as there is no need to pull the bracket off as there is a slot for the return hose to slip off. REPLACE the O ring with new on the replacement hose, pivot the bracket back in place up right, and tighten (NO, DO NOT TORQUE until YIELD). If the bolt will not move - DON'T FORCE IT. Add some WD-40, tighten and loosen until it releases. If you strip it, you will be buying a cooler too (PITA install). Good luck!