they say every 12k miles

and when i took it off there was a little oily goo where the hose meets up to the valve

the kind of goo kind of looks like food fat that gels up over night in the fridge on say some pork chops for example...

i kind of would like to know how that oily goo got there and what caused it too goo up

i change my oil every 5k miles

 

that oily goop is a mix of oil and gasoline vapors! make sure u keep an eye on ur windshield washer fluid.. dont let it turn green!

 

what you mean green? thats a new one on me...

 

what exactly is the pcv valve for? what is it?

 

http://en.wikipedia.org/wiki/Pcv_valve

 

Did you use OM PCV, or aftermarket. Do you have a part number?

 

Who is they?

 

i'm at 48 thousand, haven't replaced it once.

 

I changed mine @ 40k, i will probably do it every 30k. Very easy to do and good preventive measure. The part was about 5 bucks and it takes about 3 minutes.