Yes, engine flushing oil is still available and used - in NZ anyway. I read somewhere that Kerosene (Paraffin in some places) can be used for flushing as is an 'oily' solvent. But like proper flushing oil, it is just for a very short load-free burst of cleaning. No longer than a minute I would guess, and at low revs. As traces will inevitably remain, the next oil change should be sooner rather than later too. And only if serious gumming up is suspected. Otherwise, a couple of sooner-than-usual changes of a high-detergent oil may do the job. Good luck!