For cutting soluble oil (water-miscible coolant), the best «life-extension» setup is a side-stream filtration loop that combines a coarse prefilter (bag or wedge-wire screen), then fine depth filtration (cartridge or high-capacity bag, typically ~5-20 µm depending on nozzle/tooling sensitivity). If you’re fighting very fine grinding swarf, add a centrifugal separator or hydrocyclone ahead of the fine filters to reduce loading and keep ?P stable. To really extend coolant life, pair solids removal with tramp-oil removal (skimmer/coalescer) and-when needed-crossflow microfiltration/ultrafiltration to pull out sub-micron fines and emulsified contaminants without constantly dumping the sump.