Low Oil Pressure

My 2004 Trailblazer intermittently drops to zero oil pressure and is now starting to do this more frequently.

Oil quantity looks good, and the oil looks clean. Car drives just fine when reading zero. Sometimes when restarting the car, the oil gauge reads normal (40-50 psi). Any ideas?

Welcome to AF. I would get a mechanical gage on it the the OP sending port and see what is really happening, may only be the sending unit.

Thanks. I went ahead and replaced the Oil Pressure Sending Unit ($29). I didn't have a mechanical gauge, plus I'd have to worry about getting the correct fitting to fit the Oil Pressure Sender Port...

The Sending Unit is a little difficult to reach (without jacking up the car), but it still only took me about 15 minutes to replace.

We'll find out if that's the problem after usage, although I am convinced that it was.

Thanks again for your advice.

If you have the same problem again, reading zero. Just open the hood and pull off the oil cap, very slowly. If it doesn't look like any oil is splattering up on the bottom of the cap while holding it over it go ahead and move the cap away and look down in the hole and see what it looks like, that's the the easiest way to tell.