k & N says the filter actually filters better when its dirty to a certen point. i just cleaned mine last week and now my MAF is gone. so if you do clean it don't oil it or just bearly oil it. let it dry for 24 hrs.
When the filter turns black, and the red is gone, it's time to clean it. If you got oil on your MAF and its giving you problems, try spraying carb cleaner in it and letting it dry.
Injen recommends cleaning every 50,000 miles. Just don't over oil the filter if you clean. Let it dry thoroughly before you go driving. I have not cleaned mine yet. The car shows no symptoms of a dirty or clogged air filter.