how to maintain a metal gitzo tripod?

[studio347]

I have a big metal gitzo tripod with which I use for 4 by 5 camera.
The joint is a bit stiff now. Locking and unlocking is not easy.
Is there a good way to maintain the tripod?
Is WD40 a good thing to use?
I think I need to apply some oil to the locking system...
Thanks in advance.

[viewfinder]

WD40 is actually a dewatering agent containing largely paraffin.  Paraffin is also useful as a solvent for grease and restructured oil deposits, so you can use it to free up seized joints, bolts and fixings etc.......its unlikely to harm the tripod.      Gitzo make/provide a specific lubricant which is available in two tube packs.