Oil pressure low read ing at speed between 2 and 3 bars going up and down. and if i take oil cap off and clover with hand and rev it ' i dont see any oil on hand

Hi. Your symptoms are a strong indication of major sludge build up in the block region. This type of thick build up will clog up the oil ports, thus, reducing the normal flow of lubricant throughout the engine. This will cause fluctuating oil pressure, as well. Although this issue is a common cause of your symptoms, there are others. The next cause of fluctuating oil pressure will be a failing oil pump. This device can fail mechanically(gear failure). When this occurs, the engine oil will not circulate properly, thus causing the symptoms you are experiencing.

In conclusion, This type of problem will require you to administer a manual oil pressure test. This will confirm the oil pump failure. If the pressure test reveals that, indeed, the engines pressure readings are low, the oil pump will be the culprit. I recommend to administer a engine flush, and change the oil pump and oil pump screen, as well. Now, if the manual pressure test reveals that the pressure is optimal, this will indicate that the presser switch(sending unit) is faulty.

C'mon, *******, it's a 13 year old car, the oil pump is failing.