Replacing Zinc's

[TunaHead]

How do you know when it's time to replace the zinc's?

[reelapeelin]

When the fastener holding it in place rattles ;) ...

[76GMC1500]

I think the rule of thumb is when they're about 50% of their original mass.

[Blue_Runner]

So you are saying its about the same rule of thumb as viagra?

:o