Alternatives for mineral brake fluid / oil (in a pinch) In case you don't have 'original' bicycle specific brake fluid on hand (e.g. "Magura Royal Blood"), what might be a good alternative to use (in a pinch)
 in hydraulic (disc) brakes? (for brakes that take mineral oil).

How long would such an alternative last? Which problems might occur and how soon? 

I've read a few suggestions for alternatives:


Fork cartridge oil (the lighter (more viscous) variant)
Total / Castrol LHM Plus Fluid ( I believe it's power steering fluid)




Questions:


What are some alternative (/better) suggestions for alternatives?
Would the Total/Castrol LHM Fluid or fork cartridge oil be a good alternative?
Does anyone have experience with using either a fore mentioned options for brake fluid?
Would the heat generated by braking be an issue for either of these/other alternatives?


What are the requirements for a good braking oil/fluid?, my thoughts:


High boiling point
high fluidity


Do you agree with these requirements? Did I miss any or are some of them simply incorrect?

Any suggestions are welcome.
Thank you!
The rubber seals in mineral oil levers and calipers are very easily damaged by using the wrong fluid, and should this occur replacement seals aren't typically available. Experimenting with alternative or in-a-pinch brake fluids is a bad idea for this reason. The results are unpredictable. In the worst case, a brake failure could occur.

Running a different viscosity than intended can also alter brake performance. In particular, higher viscosity fluids have been known to sometimes cause either slower or incomplete piston return. Of course the specifics of the hose, brake, piston count, pad spring, etc are all going to play into that, a fact that no meathead MTB forum poster is ever going to consider for a hot second before telling you to go put LMH in your brakes just because they did it and it didn't blow up.

There's a type of DIYer who loves talking about how they've had their bike set up with hack X for Y years and it's totally fine, so it of course will always be fine for everyone forever. That's a good type of person to categorically ignore. Most of the time, their shadetree nonsense doesn't work as well as they want to believe, and they're really only out to appear as though they have something meaningful to contribute, when in fact the opposite is almost always true.