that's right Don. I think it is better to change engine oil every 3 months. I'm telling that because, in SL, most of car owners doesn't wash the car under body for months. The only time they wash it is when changing oil.
When talking about oil filters, there are very good Japanese origin filters out there in the market. "V!C" is only one from a list. I trust this brand. For a low priced filter I recommend S@kur@.