Hi All,
Figured I would convey my ecstatic findings of power steering fluid for our Hydroboost systems.
I had changed out my steering box (AC Delco new rebuilt) and a new AC Delco power steering pump a couple months ago- during this time I had the occasional squeal & the brake pedal travel seemed to be the same as my past 3 H2's for pedal travel...which to me always seemed excessive compared to all the other vehicles I have owned - mostly european sports cars.
I also have all new rotors, pads (atall 4 corners), new high pressure braided lines to replace the stock rubber flexible lines at the calipers. I also bled & refilled the brake fluid with new Dot3 (twice).
I had complete bled and refilled the complete system - twice, as the following method I had found online describes:

"This is compliments of Heartbeat Hauler (Jeff)
Under the hood on the driver's side next to the fire wall up high there is a rubber return line w/ a spring clip holding it on. It's real obvious and the only one there. Put some rags under the hose and around it when you pull it off or it'll be quite a mess. I removed the clip and hose, then attached a piece of clear 3/8" tubing 6.5ft long onto the fitting using a small hose clamp. Ran the other end to a catch pan on the floor. Alternately there is a pic below of how to do a hose to an empty gallon jug. Start the truck, in park, slowly depress the brake pedal as far as you can and hold it. Then turn your steering wheel clockwise 1/4 turn, back to center, then 1/4 turn counter clockwise then back to center. Slowly release the brake and re-apply and turn steering wheel again. Continue this until you hear the pump make noise (mine took 3 iterations). Stop immediately and turn off truck. Fill the power steering reservoir with fresh power steering fluid, Then repeat this procedure until you see clear fluid (in this case green) coming from the hose. Make sure that you put something on the hose in the catch pan to hold the end of the hose in the pan. Or drill a hole in the cap about 1/64" smaller than the tube per the picture below. Mine took a little over 3/4 of a gallon. Probably more than I needed but I wanted to get as much old stuff out as I could, and like I said, the old fluid was BLACK! Then, remove the clear hose and reattach the rubber return line. Also, make sure there is enough new fluid left over to refill the power steering pump when you're done. AND, after you refill for the final time, start the truck and move the wheel back and forth, then recheck fluid level, add if needed. All done."

I had tried Royal purple, I had tried genuine AC Delco spec fluid - no changes... to the point I was getting frustrated thinking that maybe this is all the system is capable of for best performance... I should have had any air out of the system in the prior refills.

So today I went to Autozone and was looking for power steering fluid ideas - and spotted what I had always used in my european cars - Pentosin CHF 11S (its a green synthetic fluid) its expensive at almost $30 a quart - I figured what the hell - my brakes were always superb in my Mercedes, BMW's, Volvos, Porsches etc.. I bought 2 cans...

I went ahead & went through the procedure of changing out the fluid & pushing the brake while turning etc... & pushed through the system the new Pentosin fluid and stopped just at the point to use both cans with final filling to top off...

Not expecting much of a change I started the H2.. OMG! My brake pedal was right up at the highest point of engagement I ever have felt- not a little change this was very noticeable and high/firm!! So being the pessimist I am in regards to this hydroboost system I went on a 10 mile drive through twisty roads with much braking & turning - PERFECT!! The steering is like butter with NO NOISE and brake pedal remained perfect with NO FADE to pedal travel!!

So, I either did not have the air completely out of the system after changing the pump &/or box OR this steering fluid is THAT good!

If anyone else tries please let us know results...

I did research this after my results of Pentosin CHF11S and found this on Amazon- (Chevy actually does use it evidently also in some applications).

& this-


Same product...

Use at your own discretion/risk however for my application - I am extremely satisfied with the result!! The directions on can state it does not mix well with others so make sure you buy enough to do a full flush of the old nasty fluid to replace entirely with this. Again, use at your own risk- I have no idea if the hydroboost Gods approve of this fluid....

Chris

 

I know that is great fluid, but I never thought about using it in applications that do not call for it. Glad it worked out great for you.