My 84 Trek road bike has the original Silca pump. It still works fine but I am wondering if there is any lube / preservative I can put inside for the seal.
Whats your thoughts, if it works don't fix it ?

not sure that it matters a lot, but I've used Phil Wood grease... mostly because it doesn't seem to break down over time. In contrast, I've seen white lithium grease dry up and get pretty solid over time.

Steve in Peoria

Petroleum jelly (vaseline) is what many of us used a million years ago. I've found with old dry pump leathers that proofide and other leather dressings work nicely to soften them.
Brent

+1 on Vaseline. That is because it is so available and it works. One of the things that think is that if it works well on skin, then it should work well on leather. After all leather is skin. Yes, I know there are differences, however, aside from the specialty creams, this generalization works.

Thanks for the info guys. I have used Proofide on my Brooks saddles, I will try it first.

Proofide is good for softening the leather if it has dried out. But after letting the Proofide soak in for a day or so I would add a lubricant such as the vaseline or greases mentioned.
Brent

In case lubing doesn't work, note that after failing to revive the pump leather on one of my three Silca Impero pumps with multiple attempts at lubing and conditioning, I decided to replace the leather. Although Silca sells leathers for their floor pumps, they don't seem to sell Impero leathers. The only place I could find them was HIGH END Used & Vintage Bike Shop! We stock Campagnolo XTR TA Suntour Parts NIB NOS

The rubber seal where you insert the tire valve can also dry out, I just had to replace one.

All the above will work but you should be aware Silca makes what they recommend we use, NFS leather conditioner and pump lube, it's not cheap for a 1 oz bottle but I figure the pumps are expensive and I expect my kids will be using them someday when I am not around.

A dab of petroleum jelly from time to time can save this, aids sealing and on /off of the chuck, all good.

Any scientific or otherwise guess what the secret sauce may be?

I have used mineral oil with good results both reviving and maintaining the seals, especially after cleaning the sludge off the inside of the main body tube.

Most of my ancient Silca's work just fine and some are cracked at the top as many are so they are fully retired from active duty, acting as a Talisman but would get you home if necessary.

At this point for me, they are mainly a flourish, so many C+V bikes look incomplete to me without one, especially if they have a pump peg, holder, etc.

I also carry an inflator/pump, spare tube, far too many tools, etc. so the Silca is mainly for fun and correctness style points for me.

My son-in-law racer swears by Nix Frix Shun the UK outfit and I suspect this is there lube plus a leather conditioner. I rotate religiously through bikes so do a lot of pumping and add a couple drops a couple times a year and my now vintage pump feels great but can't really say that it adds life as I rebuild the pump only a couple years back and use the Silca NFS on the piston gasket and Molykote PFPE on the chuck gasket.

Ahh, mad science.

I broke down awhile back and sprung for Silca's synergetic chain lube awhile back and finally just used it when I installed a new cassette. Sort of cleaned the chain checked it for stretch and on with the new, it had been jumping around a bit before but may have mainly been my crappy adjustment.

That lube made a huge difference even if the old cassette was worn, very impressed and the bottle alone is almost worth the cost, really applies it the way I like it to, very small steady drop by drop with no dripping or wasting, not a single drop on the floor and all on the chain where I want it, all good.

I come from industrial maintenance and found sometimes it is mad science and unfortunately sometimes it turns out to be mad science spin. But when it's a well established company with a reputation worth holding onto and being careful with it it is a pretty safe bet.

Absolutely, I have been a mech/tech all my life from very early on, bikes, fomoco and ASE Sr. Master tech and drag racing motorcycles twice a week for the better part of 25 years.

At work, the track, on the road and everywhere in between, combine mad science with mad and practical skills and we are golden, making $$$ and delivering many azz whippins as well as receiving plenty too.