There is nothing WRONG with a preoiler, but there seems to be no practical benefit. The reason I say this is that only the crankshaft, its bearings, and the camshaft bearings and journals benefit. The pre oiler really does nothing significant to prevent cylinder wall wear during cold start.

Since the reason an engine usually is taken apart is cylinder/piston/ring wear, valve related problems or head gasket problems, the preoiler really does nothing for the portions of the engine that usually cause the need for overhaul or repair.

This is the reason that I've never pursued a preoiler.

Have a great day,