I have a '95 Z28 with the LT1. It has 117,300 miles and is strong. Being high mileage is the only drawback. I cranked it this morning (temps around 35 and have been much lower) and it began to make a noise like a stuck lifter or valve with popping an snapping from the exhaust. It gradually subsided, but my concern is am I supposing correctly and should I use something like Marvel Mystery Oil to loosen up the internals? What other suggestions can I get? It is due an oil change. Would this possibly help clear it up?

After daylight I went back out and cranked it again and found something unusual. My wipers were making the noise I heard earlier in the dark (Yes I will admit to my phoopas). The wipers were "off", so I wiggled the wiper switch and they quit moving. Only thing is, that won't cause the popping and snapping out the exhaust pipe.