a couple months I bought a 2000 xj sport 4.0 and since I bought I have had problems with my oil pressure. when I cold start my car everything the gauge is reading normally however one the car gets up to operating temp and is driven for about 20 minutes the oil pressure drop to around 10-13 psi when i am on the gas. but onceI stop for more than about 10 seconds the oil pressure goes to 0. the car is running fine, the oil is at the recommend tick on the dip stick and I have replaced the oil pressure sensor. does anyone know what the problem is or how I can fix it?

 

You will want to temporarily install a mechanical pressure gauge to verify the pressure you are seeing on the in dash gauge.

Most of your description is normal, except for the dropping to 0 psi. My 2000 drops to 10-13 on the gauge when warm, but that is the lowest it will drop.

If it still is the same, you may have a XJ that had a cracked head, or still has a cracked head. The 2000 and 2001 were known for an issue with the head cracking, and would allow coolant into the oil which if ignored spells certain death for an engine. If it is/was caught in time, then the engine is usually fine and you may have another issue with either the gauge, or a faulty new sender.

What is the history of your XJ? Miles? How long have you had it? Does it have the original head? All of this will help all of us help you.

Are you familiar with the 0331 head on the 2000 and 2001 models? If not, Google will give you all the information you need to know to identify what head is on your XJ and how to check for a crack.

 

What oil are you using ? most people here run a 15-40w oil .