The best product on the market is a regular routine on service.
You just found another example of a Previous Owner (PO) not doing what's needed. You can find this issue in just about any component, i.e. brakes, bearings, radiator, etc.
Sure, a tear-down and cleaning resets the clock but if this is the only place you've seen it, then clean it out and each time you do a tune-up (D. 101 Crankcase Ventilation, Service Manual) - or after a couple of oil changes to ensure the engine has circulated the oil, at temperature, and done its job.
That paragraph above also points out that all the connections need to be tight to ensure no air pressure leaks - so the PCV can do its job.
I found sludge early on after getting my jeep. A mechanic suggested a gasket on the oil filler tube would help ( I didn't have one at first). I didn't have an original PCV valve so I used a generic one and saw no more sludge.