With rain coming (or already here) for much of the USA - I thought folks would like this $5 rebate from GM on AC Delco Wipers. I've found them for under $3 on Rock Auto https://www.gmpartsrebates.com/offers.asp Keep in mind, wipers are only supposed to last for 12 months
About 6 months in Florida, the sun takes a toll on them, sometimes I forget, then when I put a new pair on, I'm like sh-t, those old ones sucked! I'm at that point in life where I let them put them on, dang some of them take me forever to figure out how the snap in place! I finally fixed my Detroit Speed set up on the Z, I must have had the adapter just a few degrees off where it goes on the shaft, drivers side was hitting the trim on fast. While I had it apart knocked out the window screen trick on the plastic cowl cover to keep all the nasties out of that void.
In a cold climate where we keep cars inside and the sun isn't killing the rubber, wipers last far longer than for you guys down south. The sunlight is the killer, not time.
The cheap blades wear out much faster than the quality blades - no matter where you live. ACDelco blades are made by Trico - a quality manufacturer. That said, they have two quality levels - Professional and Advantage. You want the Professional series. The $2.79 one's from Rock Auto are the Advantage series. They have the Professional series available however. I typically get 18 - 24 months of quality performance from the Pro series.
I change mine when they fail to wipe the glass cleanly. I've never kept track of the interval. With multiple vehicles, I couldn't even guess how long they last. It just isn't important enough to document. I just replace as needed. It is kind of like, "How long does a roll of paper towels last?" I never keep track.
Rain ??? I bet the majority of cars owned by members here hide in the garage at the mere suggestion of rain. Why would they need wipers ?
True, we don't drive our Camaros in rain anymore, but we still need wipers on our other vehicles that do have to drive in rain.
Mine saw plenty of rain during the HRPT this year. In fact, had it out for an errand last Thursday and got poured on. So much for the weather forecast. The NOS Anco 16" blades and 2 speed wipers suck!