• Casio watch warranty period: 24 months

• Casio watch advertised battery lifetime: 10 years

• My Casio watch actual battery lifetime: 5 years

• I didn't have to open it until 2x the time of official warranty.

• The gasket had gunk in it on the outer side, so I cleaned it, but I could have gotten a replacement from one of the local Casio stores.

• The strap has broken 2 times until now (yeah, I'm kinda rough on it) and replacing that doesn't void any warranty.

  • The standardised nature means, I can get either Casio branded straps (even from other models if my model is discontinued) or other generic straps.

• I am nearing the point at which it might require another battery change, but either way it's worked pretty well.

• I take hot water baths with it and even though I never used it up-to 100m (I'm not really into diving), I haven't seen rust or moisture in the inside.

• Of course, if you open the stuff and change something yourself, it's up to you to warranty it. You can't expect them to trust every tom, dick and harry who might:

  1. Not tighten the screws well enough
  2. Not place the gasket back in place
  3. Do any other random stuff

and officially say that they will cover that. I know I wouldn't.

The point is, they let you do what you want and help you at a reasonable price (the replacement straps were priced appropriately).

I can't say the same for the fancier models though.

For legal reasons. Because they can't check if you didn't fuck up the gasket.