I've used K&N oiled cotton gauze filters over many years in many different vehicles with good results and no problems. They have a high CFM flow rate and do well even when very dirty.
You shouldn't clean them very often, though. Biggest mistake people make is that - cleaning too frequently and reapplying too much oil. Once every 50,000 miles is about all you need unless you are off-roading in high dust situations.
I currently run K&N's on three vehicles, an Aircharger cone on my Armada, a drop-in on my wife's Volvo, and a circular style K&N sits on top of the Weber carb on my CJ-5 Jeep. No problems with any of them.
And on all those present and former vehicles, I've never had oil get to the MAF sensor, probably because I don't clean frequently, and don't over oil. But it's easy to safely clean a MAF sensor, whatever the reason you might need to do so.
Having said all of that, I do think that the AEM Dry Flow filter, or filters of that type, are a better solution, now that we have that option. I think it will do a little bit better job in filtering out the very fine, small micron particles, although there is not much evidence that particles that small actually cause any harm.
