My Joe Blow Pro is squeaking and binding (the 'smart head' is fine). I think the cylinder probably just needs lubrication but what should I use?

Topeak's web site is now worthless and they don't even have an email address anymore. Their 'customer service' page just fluffs you off to todson.com, apparently a generic customer service company with which I'm not even going to waste any time).

Spread a film of brake fluid on the parts that see friction. Remember, bike industry is just a toy industry. Expect the Chinese made stuff to break or work poorly.
If you want precision equipment, buy a Japanese car.

Brake Fluid??? That stuff is really agressive and makes a pretty good paint remover. I've never seen it recommended as a lube for anything.

Silicone grease will work a lot better. It's not volatile and won't cause deterioriation of the inner tube rubber or the pump'e seal washer.

Car brake systems use rubber seals and plastic reservoirs. I've never had any problem using brake fluid on bike pumps.

I just pulled out the shaft. The o-ring looks ok but fits loosely, so maybe it's stretched. It's been lubricated with some messy silvery powder, which I assume is at least partially graphite.

Silicone Spray works great in pumps and won't dissolve paint, plastics or rubber.

+1 brake fluid can be murder on the neoprene O-rings and other rubber parts of the pump. Silicone grease won't hurt them so is a much better choice.

Yeah, I would not suggest brake fluid either. It's fine on some types of synthetic rubber since such rubber is obviousy used in brake systems. But generally it can really do a harsh number on a lot of typical rubbers.

A silicone grease or spray would be the obvious lube. Or a thin wipe of the parts with some ATF oil would be another option.

I'd clean off that silver gunk too. If it's an aluminium tube some of it may be worn metal. Espeically since you said it was binding and squeaking. or if it is the old lube that dried out the lumps could foul up the valving and cause it to leak the wrong ways. Best to totally clean the pump out and start with some fresh lube.

Wouldn't it be great if Topeak would just tell us what to use? Sigh. Next time I'm buying Park, those guys have always responded to my questions in the past.

Well, it's not rocket surgery or brain science, it's just a simple pump. There's any number of things you can use to lubricate it as long as you don't use anything that will affect the butyl rubber of the tubes. Basically I'd suggest you avoid anything that is directly petrochemical or, in this thread's case, brake fluid. And that would be silicone lubricants and the ATF fluid. There's likely any number of other synthetic oils and greases but since we know that silicone products and ATF oil is rubber and plastics friendly why search around making things more complicated?

Hell, a good mineral oil from the drug store would be fine as well.

Jim:

I use some left over silicone grease for lab uses like joints and rubber stopcocks. Great on vacuum pumps too and holds down to 10E-03 torr! The stuff I was using is pretty high end stuff. I think if you search at advanced-scientific.com or other suppliers, you can get a small 2 oz tub or something for around $10 or so. Never goes bad. I lubed my metal floor pumps and the ones in both my wife's and my vans and haven't had to touch them in 10 years. Heck, don't even know where my grease is. Alternatively, rubber automotive boot grease. If you change your own ignition wire set, that stuff is similar to lab stuff, but in a smaller tube for just $3 at Kragen/O'Reilly or PepBoys.

Silicone grease for neoprene and rubber is readily available. If the hardware store doesn't stock it, visit a Scuba dive shop. Divers use this type of grease for all sorts of things and a small tub of it is inexpensive (even if for diving where everything is costlier than for biking).

Hmm I wonder if I have some silicone grease left over from my years as a electronic tech - I remember using it on heat sinks, for example...

I've used a lot of it as well. If you have any be sure it's the clear slightly cloudy stuff and not the paint like white paste heat transfer compound. That paste uses a "pigment" of some powder with a lower heat conduction coefficient. It's likely not going to be the best for lubricating. The clear or slightly cloudy silicone grease that was more common way back when is just grease with no fillers. That's what would work better.

If I have any, it would probably be the white stuff. But I'll bet it would work fine. After all, nothing remotely corrosive would have been used on circuit boards.

[Update] I found an ancient, tiny tube of white heat sink grease with just one dab remaining. The ingredients are listed as silicone and zinc oxide.

Our Joe Blow was squeaking and a bit painful to use. Had some 3-In-One Silicone Lubricant spray, and sprayed it on the plunger, and a fair bit into the gap with the main pump body, and it's now quiet and working much more smoothly.