My 1999 jeep grand cherokee has a oil gadge that is going crazy. The oil level is good and it was just changed. The miles are over 100 thousand. The oil level started going down just when we would stop and quickly correct as soon as we would start to go. Now the low pressure is even when we are driving. I was told it is possibly the oil sending unit so I will try to fix this today. Their is no knocking noise so I am not sure if it is the oil pump. If anyone has any ideas as to what it is let me know.