My $.02: it depends on your answers to the following (not necessarily exhaustive) questions.
Can you live with lesser preformance on some operations?
Are you working the same materials on all machines?
Are there specs on allowable residue?
Are there disposal issues?
Are you reclaiming coolant for reuse? Can you reclaim well enough that you can use the worst contaminated in your most demanding area after reclaiming? It only takes $$$.
Might there be issues with embedding abrasives in bearing surfaces of your finished work?
We looked at this issue in a plant running cast iron, steel, and aluminum. Processes included turning, grinding and honing. We decided that we were better off to use a minimal number of formulations but all from one vendor. By doing this, we were able to drop the costs on the less critical areas and use better in the more demanding. Keeping to one vendor meant better response when requested and the volume of business was sufficient spur to action.
Griffy