Made in Racine, Wi. Got this from my grandfather, and has served me well. Still works just fine. That said, it's over 40 years old. Any preventative maintenance I should be looking at, or "don't fix it if it ain't broken"? Piston gets lubed from time to time, and a wipe down.

If what you have been doing works, keep it up.  It should be stored with at least one pump to keep the seal seated.   If I recall correctly, that one should be new enough that it does not need to be cocked to store air.  The older ones would need to be stored cocked as well since the hammer would keep the valve open.  It is easy enough to check.  If you can pump it up without cocking it, it is a newer style.

Pump first, cock, I get a pop (not a thud) as expected. So guessing it's the newer style. Weather is nice and sunny, so I broke out the chrono... ~320 fps with 3 pumps, ~550 fps with 10 pumps.

Pre Crosman Racine Sheridans really should be limited to 8 pumps.  If you chrony you'll see you get very little value past 8, and you put a lot of strain on the pump arm linkage for very little gain. I believe steroided Sheridans can pump a bit higher, but stock ones should stay at 8.

ETA- Go grab some secret sauce lube from MAC1.  Best lubricant out there for vintage pumpers like yours.

Nice.
I scored a 1968 Sheridan Blue Streak at a yard sale for $10.
It looked like it had been tied on a rope and dragged 10 miles down a gravel road.
The stock was beat-up and worn down to bare wood, and most of the finish had worn down to brass on the barrel.
But the guts seemed to be working fine.
So I refinished the whole thing.
After sanding down the stock I used Birchwood Casey Tru-Oil on it, the I used steel wool to remove all of the finish on the barrel and spray painted it with an epoxy paint.
It has a Williams peep sight on it when I got it, but I had a couple of cheap Bushnell 4x32 scopes laying around so I put one of those on it.
I probably spent way more time on this project than it was worth, but it came out pretty nice.

Attached File

It looks sweet to me. But I have a soft spot for old air rifle’s.

The old benjis and Sheridans are great rifles, I've killed a lot of critters with em.