Originally posted by theveed
copy from my HCP reply:

Blades don't last over 6-8 months, whether you use them or not, you're supposed to replace them 2x a year. Preferably the whole wiper blade assembly (like Bosch, Denso, etc) and not just the rubber blade insert.

Why? The assembly is a mix tensioner in a frame that "pushes" the blade flush to the glass, if the rubber's flex and length isn't matched with the assembly, you won't get optimal "wiping" contact.

Personally, I change blades every May or June, just before the rainy season... After the rainy season, your blades are probably worn out already from the daily usage... Your call whether to replace them or not since during the dry months, you rarely use them. But don't expect them to last you 2 rainy seasons.

Think razor blades... They're exactly the same concept.
ganon pala yun sa akin 3 years na di ko pa napaltan. makabili na nga mamaya.