If you are going to reuse the stuff after this job, make sure you strain it through some fine cloth to get all the iron residue out of the liquid. If you don't, it keeps working on the iron in suspension and wears out the fluid much faster.
Remember: It should be a pleasantly light yellow, well-hydrated urine color. The darker it gets, the worse condition the liquid (and your kidneys ) are.
This has been a public service announcement from you medic/mechanic.