The crankshaft bearings consist of several cylinders of metal (split down the middle for ease of assembly) that encircle sections of the crankshaft in areas that the crankshaft is supported by the engine block. These bearings contain orifices that allow pressurized engine oil to be squirted between the crankshaft and the bearings, thus avoiding metal-to-metal contact between these components. Ideally, the crankshaft is always floating on a thin layer of oil above the bearings when the engine is running. Ideally.
The reason that your oil pressure guage is showing a higher reading after the use of oil treatments is that the treatments usually increase the thickness (viscosity) of the oil in the engine. This is not always a desirable circumstance, as thicker oil has a more difficult time lubricating components when the oil is cold. Thus you may be trading a higher oil pressure reading for increased engine wear when the engine and oil are cold.
Take a look at your owner's manual. My guess is that it does not recommend the use of oil additives.