I changed mine at around 6000 miles and it was pretty dirty. Just started using the K&N filter. Never tried their cabin filters before but have been using their engine filters for almost 30 years and I swear by them. They are lifetime filters, so you only have to buy it once.
In the film Back To The Future, Doc Brown refers to "jigawatts" of electricity. This is the now-obscure but once-standard pronunciation of the word "gigawatt", one billion watts. Nowadays it is usually pronounced with a hard "g" as in "gander" and "gold".