Mixed synthetic and mineral hydraulic oils now the system has gel inside need help

Hi all, my mate's worker put synthetic oil into his wheeled excavator that was running mineral oil, and it's turned to gel. We've flushed the system and got some of it working again, but it's still not running well. Is there a product we can use to flush the system that might help dissolve the mixture? It's a good machine, but we've been told it'd be better to just buy a new one. Surely this has happened to someone else before. If there's a mix or additive we can put in the oil to help break down the gel, we'd really like to know. At the moment we've got nothing to lose since the machine is pretty much toast anyway and only a couple of bits barely function.

Thanks for any help, cheers Tom

I've heard about that before, but never actually seen it happen myself. Could you share some pictures?

There's no real fix for it that I know of. I'd maybe try flushing it out multiple times with a cheap 32 and see if that helps. I can check with some mates, but I reckon they'll tell you the same thing. Tough break on this one.

I'm wondering if diesel might work? You've got nothing to lose at this point anyway.

I'd test out different solvents in a glass jar first to see which one works best, then give it a go. Mix it with some cheap hydraulic oil to dilute it.

I wouldn't rule out trying various solvents, but keep in mind they could cause your o-rings and seals to swell if you actually run the machine. If you do find a solvent that breaks down the gel, you might be able to pour it straight into the tank without operating anything. After that, drain the tank and use a suction bucket with a piece of PVC pipe inserted to the bottom and corners to pull out as much as you can. Once you've removed the bulk of the debris from the tank, do one more flush with some cheap oil. That's probably your safest approach.

What if you heat it up? Would the gel turn liquid at a temperature the system can safely handle?

Did you swap out the filters before and after you flushed it? Have you blown or bled out the control lines on the functions that aren't working? I wouldn't write the machine off just yet, but you might need to dig deeper into the circuits that are causing problems.

What make and model is this big wheeled excavator? The amount of damage the contamination's caused really comes down to what kind of hydraulic system it's got. A wheel loader running gear or vane pumps can handle a lot more contamination without too much trouble compared to an excavator or something else with variable displacement piston pumps. Any machinery dealer would probably tell you that a complete teardown, cleanup and reassembly would be the bare minimum. I wouldn't take on repairs on a machine in this kind of shape without some paperwork protecting me from any future problems that come up.