In weighted, oil-base mud applications, decanting centrifuges are operated in series. The first unit returns the coarse solids fraction (weight material) to the active system, with the light, liquid fraction being routed to a holding tank (rather than being discarded as in a classic weighted mud application). A second unit, often a higher capacity machine, strips out the solids and discards them, returning the effluent to the active mud system.

This process is not as effective as a single unit for viscosity control — a large portion of the colloidal size solids are returned to the active mud system in the effluent stream of the second unit — but the effluent stream from the first unit is too valuable to discard, especially with synthetic oil muds. Usually the coarse solids fraction is discarded and the base fluid is retained for re-use.

In oil based mud applications, a kind of vertical centrifuge - Vertical Cuttings Dryer is often used for drying the drilled solids in order to reduce the drilling waste volume.