Just put a new head gasket in the 4.0 last week. The jeep has been driven about 150 miles since. No oil or water leaks to date. Today for the first time while sitting at a stop light I noticed the oil pressure at 0. I stopped and checked the oil. Found it was about 1 quart low. But still no water in the oil.

Although while sitting still at lights the pressure would drop to 0 at times it would hover around 10. While driving it would normally hover at 40. Now it is just making 25 30.

While sitting still and the pressure at 0 there are no strange sounds like tapping or anything else. When I shut the engine off after sitting for a few minutes with no oil pressure on the gauge i still heard the same amount of oil trickling down through the engine.

What should I look / listen for? what should I do next?

Thanks in advance for your help.