losing oil pressure sr20det

[jnash240]

So I had an issue,with top end noise recently and fixed that it was a bad fuel pump. I bought the car already swapped from a friend for dirt cheap he just needed money.so this morning I started it to drive to work to change the oil and I've been keeping an eye on the oil pressure and at start up it was perfect right at 80psi. Went to the gas station and it was idling at 20 psi. As I got further down the road oil pressure started dropping. 5 miles from the station came to a stop light and the pressure was about 13 psi at idle. Then 3 mile from there came to a stop light and pushed the clutch in and the pressure dropped to 5 so I pull into the sheetz there and it started to have a bottom end knock. I cut it off immediately and checked to oil and it is super thin . The car has been sitting for over a year and I was wondering if just the oil is old and thinning out cause pressure to drop and the bottom end knock. I didn't see any dents in the oil pan either so I don't think the Pick up is bad. Any suggestions would be great. Thanks

[jnash240]

And I also didn't see any metal shavings in the oil on the dipstick so I hoping that the bottom end isnot fried.

[PapaSmurf2k3]

I'd start by changing the oil and see what happens. Its cheap enough. You might want to cut your filter open too to see if there's any chunks in there. If the oil was contaminated with gas at any point, it could definitely be causing issues.
5psi is pretty low, but everything else you mentioned isn't out of the question.