I own a 2005 Chevy Trailblazer. My oil pressure

indicates a problem oil pressure sender unit
have the oil pressure checked using a mechanical pressure gauge and if OK then replace the sender unit or gauge

Replace the oil sending unit. On top of the engine, in the center by the fire wall.

Well it could be the sending unit for the gauge.
But odds are the oil pump or engine bearings are worn out.
As the engine warms up, the metal spaces expand and the oil gets thinner. The oil pressure drops some under normal conditions, but not more than 10 or 15psi. Normal idle pressure with the engine warmed up is probably 25psi.
You could check oil pressure with a mechanical gauge to make sure its not the sending unit.
Once the oil pressure starts staying below 20psi for long periods you'll start hearing noises.

The oil sensor sending unit is shot,

The correct way of checking this is to put a mechanical test gauge on the engine and check the actual oil pressure. (your gauge is electro mechanical and it could have a "dead spot" in it.) However, if you don't have a test gauge, buying one or having a shop test it will cost you far more than the actual sending unit would. Therefore, providing that the engine isn't knocking or tapping while the gauge reads "0" ( which would indicate that the pressure was indeed low) I'd suggest that you replace the sending unit and see if it corrects the problem. The unit generally costs around $25.

It sure sounds like the oil sending unit is at fault,now sometimes,not always,the oil sending unit will seep oil or leak oil if they go bad,but like I said,not always,change the unit,and the oil and filter just for precaution.

I have this same problem with my 2002 trailblazer; however, I goofed up and had a mechanic look at it, since I was perplexed as to what was going on with it. He told me the oil pump needed replacing and it ended up costing me around a $950. Needless to say, it still happens. A grand down the drain - it wasn't the oil pump. The oil level is always good. This generally occurs when I've run the vehicle for a while and then come to a stop. It occurs quite often during the spring/summer and doesn't happen all that much during colder months.

Check or replace the oil pressure sending unit.

You had better check your dipstick and see if you have any oil showing on the stick? Sounds like your oil pump pickup is uncovering in a turn and cavitating which is caused by low oil quantity.

Sounds like the sensor is failing.Have oil pressure checked with a mechanical gage to confirm. A new sensor or wiring repair is allot cheaper then a new engine!!