So I'mreplacing The oil pan gasket on my 98 this weekend and wondering if I should just go ahead and replace the oil pump since I'm in there. And if I do, is the Melling oil pump from Auto zone a decent replacement.

 

IMO I don't replace parts for the heck of it. I would take it apart and inspect & measure. I would also visually inspect and plastigage the bearings,especially the rear main since you will have it off anyway. What I like to do is blow compressed air into the oil galley (at pump outlet) to check the cam bearings.
YES, the Melling oil pump is fine...just don't use a high volume pump.

 

I did the RMS and oil pan. And I decided to replace my oil pump too because my XJ had over 200k on the clock and who knows if or when the oil pump has ever been replaced. And I didn't want to pull everything apart again. Plus the pump is only about 80$ so just for good measure I went for it.

 

I replaced mine with a std Melling when I had the oil pan gasket replaced and there was a difference in oil pressure afterwards, not a whole lot but some. I had the same reasoning, why not?

 

I figure if I'm in there I might as well. My Jeep has over 200,000 miles so it couldnt hurt, my oil pressure is good, going to the RMS while I'm there also.

 

Make sure you prime the pump before firing it up. I just removed my fuel pump relay and turned over the motor 3 times for 10 seconds each. Of course this was after everything was put back together.