How to prolongue life of zamak threads?

The main problem I've found with zamak razors, all of reputable German manufacture, is that, once the plating starts to go (usually on the long edges of the top cap), the rest of it lifts off pretty quickly, and the zamak underneath starts to corrode; which I think is a form of de-zincification. These are razors I bought back in the 70's, and used them until they gave up. I have no idea whether the quality of materials and plating were better or worse then than today's zamak models, and I've bought only a couple (an R41 and a Parker with zamak head and brass handle) in the last 10 or so years.

My experience suggests that the process begins mainly in razors I've used a lot, and is probably down, in part, to wear. As @Satanfriendly says, minimal tightening will help preserve the threads for longer, especially when the handle is hard stainless on to softer zamak; and good cleaning and drying can't be a bad thing. Having a few razors in a rotation is also a good idea.
Any ideas about lubrication? I'm using a rub of soap.
I use silicone grease in a tube; the type that plumbers use, and which has a multitude of other uses. It's waterproof, clear, stays put, and you don't need much. It's my "go to" lubricant in razors, especially those with aluminium threads into aluminium or stainless handles (or vice versa).

I also use it for the thread sealant on "eyedropper" fountain pens, so there's always some about the house.
There is no such thing as a zamak thread.
The threaded shank will be carbon steel and either galvanised or chromed.

I wouldn't use soap as lubricant because it absorbs water easily. I wouldn't use oil or a grease because it's not something you want next to your skin.

I use Vaseline on my razor threads regardless of the make or model. And only a very very thin smear as it will still hold moisture.

Best thing for razors is to clean them regularly and not store them in a damp bathroom cabinet.