Low oil pressure and internal coolant leak

I have a 2000 Jeep cherokee with 61,000 miles on it. It is in mint condition. There are two issues and I wonder if they are related. The oil pressure gauge goes to 0 when the RPM drops at a stop light. It goes up when the rpm’s go up. I have replaced the sending unit and the oil pump and still no change.

I also appear to have an internal antifreeze leak. I have yet to confirm this with a mechanic but I don’t see any leaks outside, have installed a new radiator, and still need to add every month. Could these problems be related. Could it be a cracked block? Could a head gasket cause both problems? What about a intake manifold problem?

I don’t think they’re related. I suggest having the oil pressure measured with an accurate gauge to determine whether or not it’s really going to zero.

There are tests to determine whether or not a head gasket is leaking. This is not something you want to guess about.

How much coolant do you add each month?

I did have a mechanic bypass the gauge with his own and he did say that I had pressure and that it did go down to about 10 at stoplights. From what I heard, it should never go below 10. I add about a quart of antifreeze per month. You should know that I have researched this a bit online and there are some comments out there about this engine developing a crack in the block. It is the straight 6 cylinder. My thought is that if the crack is in the right spot, it could also leak antifreeze as well as cause low pressure. I own a 2003 Jeep cherokee and the oil gauge never moves at all. Do you have any other advice? I will take all I can get.

I would guess a head gasket problem. That could allow the coolant to escape directly into a cylinder when the engine is hot. Does the engine show any signs of missing on start up? I would suggest a compression test to see if you have a bad cylinder.