air filter change

Hi Guys. I picked up my 2003 H2 pewter in colour and fully loaded last week.This is just an awesome vehicle to drive. My question is about when the air filter should be changed. I know with my car I should be able to see light through the filter. If it looks too dirty I change it. When I took out the Hummer air filter it is alot thicker and I can,t see through it. How do I know if it needs changed? Also on the intake tube I have a small clear tube with some coloured discs inside and on it it says "press button to reset". By any chance is this to tell me when to change the filter? I can,t find anything about this in my owners manual. I hope this doesn,t seem like a dumb question.   Thanks   Doug

if you can tap the filter on your driveway and a bunch of grit comes out, it's time to change it.  since you just bought it, it would be a good time to change it anyway, since you don't know what it's been through.  they're spendy, but worth having a clean one.  there are some after market rechargeable filters available, better to spend $100 once and a few minutes cleaning than $75 every time you need a new one.

and the discs are there for you to reset after you replace it.  When the air flow gets restricted the dics start to go to the red....