Bicycle Mechanics - Rust on my Zefal hp pump

I grabbed my Zefal hp x 3 pump yesterday and noticed rust forming on the center shaft. This doesn't seem unusual given the fact I've had to pump many a flat in the rain. . . my question is what is the best way to prevent the rust without harming the innards of the pump. I fear that a petroleum based lubricant will deteriorate the plunger since it appears to be rubber when I examined it. Anyone know the best substance to lubricate the plunger and/or protect the metal shaft from rust?

There is a lubricant made especially for rubber o-rings. It looks like Vasaline, so you could coat the shaft and it would stay there a long time. You would probably have to get it at an industrial supplier.

You can get o-ring safe grease in the plumbing section of most decent hardware stores. It's called, well, plumber's grease. :)

Same thing happened to mine. I removed the rust with a fine grade emory cloth and occasionally rub down the shaft with a fine coat of grease, and wipe down with a paper towel so there's really nothing left except a very thin film. For lubing the guts, I use a spray lube similar to WD-40, except it supposedly has more silicone. I spray a little on a paper towel (not so much that it's dripping), and rub it on the inside of the tube with a coat hanger or something similar, then use a dry paper towel to remove excess. Then I give it several good, hard pumps with the nozzle end pointed down to blow any other excess out (don't want it in my tubes!).

I've been doing that for several years, and the hp-x is still doing fine.

Thanks all. I was considering a silicone-based lube also.