Flushing Hydraulic System

[BXTotal]

I am planning on changing over to biodegradable UTF on my CK20 HST.

One problem is that it is not really possible to completely empty the hydraulic system of its current contents (non-biodegradable UTF) so if I make the changeover in the usual way, I will still have a fair bit of non-biodegradable UTF in the system when I am done.

I am looking for a strategy to reduce the amount of the old fluid left after the changeover. One thought I had was to empty the sump, add a minimal amount of the new biodegradable fluid, run the system, and dump what is left in the sump. This would dramatically reduce what is left of the old fluid. The downside is that I end up throwing away quite a bit of expensive biodegradable fluid. Anyone know how much fluid I would need to have in the sump to get the system to circulate fluid through all the circuits ?

Any other ideas of how I could purge the system of the old non-biodegradable fluid ?

 

[o2batsea]

Um, regular old hydraulic oil is biodegradable as well. Plus, since it doesn't run thru an engine where it would combine with all sorts of nasty, it's pretty benign. So I guess I'd say drain as much as you can and fill with your new stuff. You aren't going to deep fry chicken in it when you're done with it are you?

 

[Coyote machine]

Why change it to begin with?:confused2: If you change the filters as scheduled you can just top off the existing fluid.