Several Months ago, there was some discussion about aftermarket oil filters\nfor the Sonata. I had purchased a Fram PH9999. I took several pictures of\nit - the filter, O rings, and took similar pictures of the genuine Hyundai\nfilter. Matt Whiting had the following to say: "The pictures are very nice.\nIn the pictures, it appears that both the filter media and the inner o-rings\n(I think they are o-rings anyway) are a different color from the Hyundai\nfilter. This may be inconsequential or it may mean that these materials are\nmaterially (pun intended!) different from the Hyundai filter. I'd want to\nknow if this was my engine."\n\nWell, Matt hit the nail on the head. Around the end of August, I did an oil\nchange, and installed the Fram filter in my 2006 Sonata. All was well until\nI noticed the oil stain on my driveway yesterday. (My wife drives the car).\nThis morning, I looked under the hood, and found oil had been leaking from\nbetween the cap and the filter housing. I tried to give it a turn, and found\nit tight. I started the engine, and the entire filter housing was almost\nimmediately covered in oil. I took the filter cap off, hoping that it wasn't\ncracked.\n\nIt wasn't. The O ring for the cap was flat. It actually had hardened. I've\nchanged the oil in the car like 6 times now, and the Hyundai O ring was\nstill round and soft (flexible) when replaced. The Fram O ring actually is\nnow flat on the outside, and was really hard. I have pictures of the Hyundai\nO ring I replaced it with up against the Fram O ring I removed. My server is\ncurrently dead, so I anyone's got either a way to host them, or suggestions\nas to how I can link to them, let me know (my email address is valid), and\nI'll either email them to you, or follow whatever instructions so everyone\ncan see.\n\nI think a contributing factor was the cold weather we had the past few\ndays - pretty close to 30. I would have noticed the oil on the driveway, and\nthe way the oil flowed out, it would have made a really big puddle, and ran\nthe oil level down in the car. I suspect that as soon as the oil warms, it\nquits leaking.\n\nI figure there's no point in trying to contact Fram about this - I can\npicture how their customer service would react - denial.