Checking the fluid at oil changes isn't nearly often enough (and I hope people realize that dealers don't put their expensive mechanics on the oil change duty, they hire the same entry level person the quick change places do). I check all fluids, tire pressure and lights monthly and have some spare of each in the vehicles. kids actually enjoy doing it, they walk around and tell me if all the lights are lit up (I do it in the evenings so I can see the reflection off of them to verify).