"pb" wrote
The black piston won't take kindly to being frozen, I always take mine
out every year and keep them in the house. As for WD, it's not a good
lubricant, use 3 in 1 or similar on the hinges and all moving parts.
How long they last depends, mine are at least ten or fifteen years old.

Quite agree about WD40, it is good at banishing damp and at creeping into
places but will evaporate quickly, so if I want to lubricate something I
apply some proper oil (engine oil) and then the WD40 which takes the oil
into the places it would not normally get.

--
Regards
Bob Hobden