1994 Gmc Sierra question

[Marsal420]

We'll just changed my oil tonight and i realized we'll actually a few of my friends heard a noise comming from the engine bay, They suspect it may be a valve tick. We'll this engine was a used one and i dont know if it is normal for it to mk that noise after an oil change or is it because i used a sythetic blend for the first time on this truck or what. But even as i was driving home i noticed that the oil pressure gage would gradually drop and then raise and then finally it just continued to drop. I then got to my house and turned the truck off and restarted it and noticed the gage didn't move what so ever it stayed about a hair shy of the red area .

I honestly dont know what this can b because the engine was just put in not more then a few months ago and only thing i can think of is because it's a used engine and the previouse owner didn't do we'll on taking care of it or what?

If u have any ideas it would b greatly appriciated.

THANKS

[Bob B]

Boy that's scary!
Sounds like the oil pump isn't pumping. I'd hook up a real gauge on the engine to see if there is any pressure.
I've heard of some engines like Range Rover loseing the prime if you change the oil and the filter at the same time, but I haven't heard of this on chev or GMC.
BTW, the Range Rover engine originated from GM though.
Good luck,
Bob B